Yet the term can be used, and in dozens of places in or around many British cities. How else do you describe an area which taxi drivers refuse to serve, where doctors are advised to seek police protection before making house calls, and which the police themselves will only visit in numbers? What do you call an area where the majority of law-abiding residents lock themselves in their homes in fear of a lawless minority?
In the map on the opposite page, we identify 40 areas around the country which local residents, the emergency services, transport and service industry workers regard as places which, for reasons of personal safety, they would rather not visit.
It is not an official designation, nor has any official body drawn up a similar list, as far as we know. But in practice many people are treating them as no-go areas. As one police officer put it last week: 'No sensible outsider would go to one of them at night.'
Take Toxteth for example. Merseyside taxi drivers often refuse to go to parts of Toxteth. Salesmen and milkmen are equally cautious, following a number of attacks. A man delivering bottled gas there was held up at knifepoint by three youths earlier this month. His mobile phone and money were stolen, his windscreen smashed.
In no-go areas many services regarded as routine elsewhere in the country have either been withdrawn or are provided only when police protection is provided. This is the result of bitter experience.
Earlier this month doctors called for greater protection after a survey revealed that more than one in five had been assaulted in the past year. GPs reported being hit with bricks and slashed with knives. Many of these attacks have happened in the sort of places listed opposite. The figures were highest for GPs in inner cities; nearly a quarter said they had been assaulted during daytime home visits and 21 per cent during night visits.
Dr Jeremy Menage, secretary of the Local Medical Committee in Coventry, explained: 'Doctors are often travelling on their own and may be carrying drugs that people may want to steal. A number of doctors in Coventry have been assaulted - a lot just don't want to do their own visits out of hours.'
The British Medical Association is so concerned it has issued doctors with guidelines for visiting areas they regard as dangerous: they should ask for police escorts; they should not carry their doctor's bag, but instead should hide drugs and equipment in their pockets; when they use their car, they should ask a relative of the patient to look after it; they should never display their 'doctor on call' sticker.
Dr Eric Godfrey, chairman of the Local Medical Committee in Manchester, said practices with female staff refused to send them out into Hulme and Moss Side. About 90 per cent of house calls in the city are farmed out to doctors working for agency services which provide drivers in radio contact with a central control room.
Dr Godfrey said one of his trainee doctors was forced to give up his medical bag at knife-point by two youths who cornered him in a tower block. 'I have gone into parts of Alexandra Park as a police surgeon and I have been scared stiff. I have been into certain parts of Hulme and the police have told me not to go in without them.'
Dr Menage foresaw grave consequences for the medical service: 'Fear of assault is one of the pressures on the whole culture whereby patients expect a visit from a doctor. I think there may come a time when doctors are no longer obliged to do home visits under their terms of service.'
Another group that is exposed to danger are postal workers. In some inner-city areas such as King's Cross in London and Moss Side in Manchester, they are now doing their rounds in pairs. Elsewhere, many have been issued with personal alarms.
Council officials whose jobs bring them into contact with the public also consider themselves to be vulnerable. Joe Williamson, an official of the Unison trade union in Newcastle, tells the story of a Gateshead social worker who was forced to retire after being attacked and beaten by a mob who were trying to get at a woman they believed was abusing her child. In Tyneside's Meadow Well estate, Mr Williamson says, gas board officials were shot at with a crossbow as they drove through.
The emergency services have no choice about where they go. Firefighters now receive thousands of malicious calls every year luring them to problem districts where they may be attacked or exposed to danger from fires deliberately set - effectively traps. Dave Higgs, national spokesman for the Fire Brigades' Union, said firefighters were increasingly being targeted for mindless attacks. Crews have been shot at it in the South-west and in Manchester, he said.
The people most likely to be called to troubled estates - and once there, most likely to be attacked - are the police. While police commanders carefully describe some estates as areas with special policing needs, the officers who work on the ground are less reticent.
Mike Huby, vice-chairman of the Greater Manchester Police Federation, said officers there listen intently to police radio and when they hear colleagues being sent to a reported incident in a dangerous area, they will drop what they are doing and attend the scene until they know it is safe.
'There are no 'no-go' areas,' he said, 'but officers are more aware of the danger in some parts. In less violent areas, officers would just be listening out for jobs that were for them. But on beats where it's very violent, each person wants to back the other up, even when the call is just to a domestic incident.' He said youths on the Ordsall estate in Salford and Manchester's Moss Side and Cheetham use radio scanners to track police movements before attacking patrol cars.
In one instance police interviewing a prison absconder before he was due to be returned to jail learnt of a plot in Cheetham to target a specific officer. 'Trees had been cut down on a bank and the idea was to ambush him by rolling logs down to hit his car. What happened eventually was that someone else's patrol car was firebombed by mistake. It was a direct attempt to target this one police officer the youths thought had been too vigilant in their area.'
Mike Bennett, chairman of the Metropolitan police federation, says it is obvious that fear of crime would be greatest in depressed areas. 'Vandalism, graffiti, they all add to fear. Michael Howard (the Home Secretary) is making all these noises but he's not coming up with the goods. I am in awe of people who do the job nowadays. I just think that the job itself stinks.'
Last week police commanders called for officers to be armed with pepper sprays. Mr Bennett said in the long term policemen will have to be fully armed: 'British police are entitled to as much protection as their French counterparts and it was only a matter of time before someone tests the matter in the courts. I don't see why the people at least risk - the upper management - should make the decisions.'
The notion of territory is central to the state of mind that creates no-go areas. Criminals seek possession of 'their area', and 'outsiders' are seen as fair game, according to Paul Rock, professor of sociology at the London School of Economics.
The areas tend to be geographically separate. ''It is not just inner city areas but remote estates like Blackbird Leys in Oxford,' he said. 'As public transport deteriorates they get worse.'
The estates are also marked by higher than average unemployment. The national average is around 11 per cent. Virtually every area in our survey is significantly above that. Government ministers deny any link between unemployment and crime, although evidence to the contrary is mounting - a recent survey by the Association of Chief Officers of Probation, for example, showed that almost 70 per cent of 28,000 offenders were unemployed.
Professor Jock Young of Middlesex University, says that the map of Britain shows a close relationship between the areas of high crime and areas of high unemployment. 'There can't be a criminologist in the country who would deny the relationship between economic deprivation and a marked increase in crime,' he says.
He believes the Government's approach to the problem is way off target. 'They seem to be going back to the 1979 approach of 'let's throw money at punishment'. That didn't work and for a long time they underplayed crime, though there were some truly dreadful things happening around the country.'
Professor Rock believes that beyond the geography of unemployment, there is a geography of crime. The no-go areas tend to be difficult for police to patrol, almost as if they had been designed to foster crime. They often have cul-de-sacs which prevent pursuit, as in the Alexandra Park Estate in Moss Side, or overhead walkways, as at Broadwater Farm.
If problem areas are distinguished by high numbers of offenders, they also have higher than average numbers of victims. Victims come in many forms. On the Ely estate in Cardiff last June, Les Reed, 46, told a gang of youngsters to stop kicking a bollard. They stopped kicking the bollard and kicked him, to death. Pathologists found 55 separate wounds on his body.
Last November Laurence Brown, 18, was charged with attempted murder after two men were shot in Moss Side district. The case was dropped because his two alleged victims would not give evidence. Last week Brown was in hospital after he was shot in a car chase.
When your home is in one of these areas, the term no-go cannot apply. Instead you have fear. The killers of Les Reed are in jail or youth custody, but who in Ely would tackle vandals or thieves now? Mr Reed's neighbours are more afraid than ever.
As for reporting crime to the police, or giving evidence in court, in such areas it can be out of the question. 'There is fear about informing, about going to the police, for fear of reprisals,' according to Professor Rock.
In such an atmosphere, crime can be thorough. In parts of Liverpool crime statistics are said to be turning downwards because insurance companies are refusing to insure goods. Sometimes thefts go unreported because there is no claim, but sometimes now there is simply nothing left to steal.
Senior police officers, acutely aware of the potential political impact of their comments on such areas, refuse to identify problem estates. But people are taking matters into their own hands. Some are setting up vigilante patrols, others are paying security firms to do the work for them.
David Shattock, chief constable of Avon and Somerset police, said last month that underfunding of police forces was creating a growing gap which was being filled by private security firms. Avon and Somerset has the highest number of private street patrols of any police force.
Local authorities, while spending millions on improvements to the fabric of such areas, often backed by Home Office Safer Cities Funding, also refuse to acknowledge the existence of problem areas.
There is no typical look to such an area. A Home Office research project on two estates in London and Humberside found that the Hull estate, semi-detached terrace houses with gardens, had much higher crime than the ugly, concrete, system-built barrier block of flats in Docklands.
If the no-go estates have anything in common, it is large numbers of young males. Usually they were born in or brought to these areas when they were newly built or newly developed, and they have grown older as their surroundings have slowly crumbled. Increasingly, they need something to do with their time. 'High child density leads to high public crime,' according to Professor Rock.
And there is another factor. Lord Scarman, who presided over four major inquiries into civil disorders, most notably the Brixton riots of 1981, said last week while social deprivation and the architecture of problem estates was important, 'ethnic differences are very important too. These are only general comments; if everyone was wealthy nobody would bother about the colour of people's faces. But unfortunately not everyone is wealthy. Incoming immigrants create problems in poverty-stricken areas where there is already chronic unemployment and lack of money.'
IF OFFICIALS are reluctant to admit to the existence of no-go areas, let alone list them, it is not just because they would be accused of permitting a breakdown of law and order. Identifying them can actually make things worse.
Many areas with high ethnic minority populations which have had serious problems in the past now have false reputations. At Broadwater Farm, for example, the stigma of the notorious riot of 1985 has continued even though the estate has changed for the better. 'People tend to 'red ring' them,' Professor Rock said. 'People from those estates then find it difficult to get jobs.'
Understandably, local authorities are keen their estates should not be tarred with too dirty a brush. Val Smith, an Oxford councillor who lives on Oxford's Blackbird Leys estate, insists that the area's reputation, earned 18 months ago when scenes of joyriding in the streets dominated the news bulletins, is unfair.
'People are surprised how nice it is when they come here,' she says. 'The pensioners all go out to the bingo, so it's not like they're afraid to go out at night. A lot of work has gone into the youth club; we don't have the highest crime rate in Oxford by any means. We've got a reputation because of what happened here.'
Of course there is nothing new about tough districts ruled by crime. Campbell Road in Islington, an area where thieves and prostitutes congregated, was considered between the wars to be 'the worst street in London'. It was claimed that - like its modern counterparts - police would not walk there alone.
'These areas have always been there,' Professor Rock said. 'What brought it into public view was the collapse of Ronan Point in London, which drew attention to the estates. Then came riots. Then we had spectacular flouting of the law, like the joyriding at Blackbird Leys. It all looked terribly dramatic, so it brought in the media. Before, the estates were isolated, semi-private. But the people who lived in many of them always knew they were ghastly.'