For one thing, it's ambiguous. The first use of convenience as an adjective, rather than the noun it had always been till then, arrived about 40 years ago to describe the sort of food you could unwrap and heat up to give you an instant dish. Some people, including me, were never too keen on convenience food, despite the cries of delight from the happy families that advertised it on television. However, this is not necessarily the sort that is sold in a convenience store. Sainsbury's new outlets will provide "quality fresh food and meal ideas in locations close to where people live and work", its chief executive has said. So the convenience of convenience food is quite different from the convenience of a convenience shop - one saves cooking, the other travelling, and it's silly, if not positively confusing, to use the same word for both.
And why use the noun when the adjective would have done? Everyone would have instantly understood the difference between "convenient food" and "a convenient shop". Of course adjectival nouns can be useful, even essential (a health warning, for example, is obviously not the same as a healthy warning), but this particular one is not only inelegant but unnecessary.
There is also, it seems to me, something rather pompous about the word itself, something ever so slightly hypocritical. For this one can perhaps partly blame its use as a euphemism for a public lavatory, but that's not the whole of it. It has certainly deteriorated with age.
St Paul's Epistle to the Romans has a fearsome list of "things which are not convenient". They are unrighteousness, fornication, wickedness, covetousness and malice, and he tells the Ephesians that filthiness, foolish talking and jesting are not convenient either. This is the Authorised Version's word for the Greek anekonta, meaning inappropriate or unseemly - the opposite of the Latin convenire, which originally meant "to come together", then "to be fitting" or, as one might say now, "right and proper".
St Paul sounds absurdly prosy when he talks of wickedness not being convenient, but this just shows how much the word has degenerated. In 1611, when the Authorised Version was published, it could suggest moral probity; today it's more suggestive of self-interest. We have convenient excuses for not doing what we ought to be doing, "Not convenient" probably means "Can't be bothered".
The rot set in fairly early. Smollett was calling a spittoon "a convenience to spit in" in the mid-1700s, and William Cowper made gentle fun of the word in his charming mock-heroic essay on the sofa, first published in 1785: "Thus first necessity invented stools,/Convenience next suggested elbow chairs,/And luxury invented sofa last." After that it was hard to take convenience too seriously.Reuse content