【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).