atrocious

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Extremely evil or cruel; monstrous: an atrocious crime.
2. adj. Exceptionally bad; abominable: atrocious decor; atrocious behavior.

Century Dictionary and Cyclopedia

1. Manifesting or characterized by atrocity; extremely heinous, criminal, or cruel; enormously or outrageously wicked.
2. Very grievous; violent: as, atrocious distempers.
3. Very bad; execrable: as, an atrocious pun. Synonyms Wicked, Scandalous, Shocking, Flagrant, Heinous, Infamous, Outrageous, Atrocious, Monstrous, horrible, villainous, flagitious, diabolical, agree in expressing great and intentional badness, calling for strong abhorrence. Because they are used with feeling, the recognition of their differences is not always practicable. Flagrant and heinous are hardly applicable to persons; the others apply to persons or things. Wicked is the generic word, and is the lightest where all are strong; it is the one that is most common in a playful use, yet it is at times an intense word, as forcible as any of the others, though less definite. Scandalous means offensive to decency, and so disgraceful. That which is shocking, literally, gives a sudden and heavy blow, and hence produces a corresponding feeling of horror or disgust, or both. That which is flagrant, literally, flames into notice, and hence is glaring, striking, and so notorious, enormous in badness. Heinous means hateful, and hence aggravated. That which is infamous is worthy of a total loss of reputation, and hence has a reputation or character of the worst kind, especially for baseness. Outrageous means attended with outrage, doing outrage, especially outraging decency, going beyond all bounds, like the acts of a madman. Atrocious is primarily fierce or cruel, savage, bloody, and wicked, enormously wicked, hence violating the first principles of humanity or of human nature. That which is monstrous is so bad as to be out of the course of nature; a prodigy or miracle of badness. See abandoned, criminal, irreligious, and nefarious.

Wiktionary

1. adj. frightful, evil, cruel or monstrous
2. adj. offensive or heinous
3. adj. very bad; abominable or disgusting

GNU Webster's 1913

1. adj. Extremely heinous; full of enormous wickedness.
2. adj. Characterized by, or expressing, great atrocity.
3. adj. obsolete Very grievous or violent; terrible.

WordNet 3.0

1. adj. shockingly brutal or cruel
2. adj. exceptionally bad or displeasing
3. adj. provoking horror