Horrible, horrid, horrific, horrendous mean inspiring horror or abhorrence.
Horrible (see also FEARFUL 2 ) is the general term for what inspires horror.
Horrid, often practically synonymous with horrible, sometimes carries a stronger implication of inherent or innate offensiveness or repulsiveness. In modern colloquial usage the word is often weakened to a general term of aversion.
Horrific (see also FEARFUL 2 ), a somewhat bookish term, stresses the power to horrify.
Horrendous is used chiefly in producing a literary effect (as the suggestion of extreme frightfulness, an apt rhyme for tremendous or stupendous, or an onomatopoeic rhythm).