"It's a horrid, horrid thing," said Lord Snowdon, lamenting the suicide of his former mistress, and we feel for him in his anguish. It must be a long time, though, since I heard horrid used like this. It's generally much more trivial. "How horrid for you," we say to a friend who has been stuck in a tube, or caught in the rain, or otherwise inconvenienced. When it comes to the real thorns of life, people tend to rely on words like dreadful or terrible, a terrible accident being far worse than a horrid one.
But horrid, in its time, has played many parts, from straight to farcical via melodramatic. There's a grim passage in Virgil where Aeneas lands on the Thracian shore and, having made sacrifices to Venus and Jupiter, starts pulling up some myrtle bushes with which to adorn the shrine, whereupon blood spurts from their roots. He has just called the plants horrida myrtus, and when I first read this it gave me a sinister sense of foreboding; but all he was saying was that the myrtle was a spiky plant - there was no particular threat in it at that point. However, horridus did mean frightening as well, presumably because fright made one's hair stand on end. Horrere meant both to bristle and to dread. (When Virgil called the giant Polyphemus a monstrum horrendum he meant it was fearsome, not shaggy.)
In classical English it was mostly the poets, like Dryden and Pope, who used horrid in its bristly sense. Among non-poets it gradually became less alarming, until it did no more than give Austen's Gothick-novel-reading Catherine an agreeable shudder ("Especially frequent as a feminine term" said the OED in 1898), and it had been a mild intensifier, as in "We're horrid early", well before Jane Austen. Its final indignity came from the lips of such as Violet Elizabeth Bott - that odious child invented by Richmal Crompton - who doubtless pronounced it "howwid." Now perhaps its having a comeback, as monstrous and abominable have already done, which can't be bad.