The word irascible means easily angered or irritable. Its antonym is placid, which means calm or serene.
Opposite words: Placid, Calm, Peaceful, Easygoing, Serene.

The word abate means to reduce in intensity or amount. Its antonym is enhance, which means to increase or improve.
Opposite words: Enhance, Intensify, Amplify, Augment, Strengthen.

The word deviant means departing from the norm or standards. Its antonym is regular, which means conforming to a standard or expected behavior.
Opposite words: Regular, Normal, Conventional, Standard, Typical.

The word acrid means having a strong, unpleasantly sharp smell or taste. Its antonym is sweet, which implies a pleasant and agreeable taste or smell.
Opposite words: Sweet, Pleasant, Mild, Fragrant, Aromatic.

The word startled means surprised or alarmed. Its antonym is relaxed, which implies calmness and lack of tension.
Opposite words: Relaxed, Calm, Composed, Unperturbed, Peaceful.

The word ostentatious means showy or pretentious. Its antonym is reserved, which means modest or unassuming.
Opposite words: Reserved, Modest, Humble, Unpretentious, Subtle.

The word morbid means an unhealthy or abnormal interest in disturbing subjects, or it can refer to a diseased state. Its antonym would therefore be healthy, as it represents the opposite state of wellness or soundness.

Opposite words: Healthy, Wholesome, Cheerful, Normal, Vigorous.

The word quiescent means inactive, at rest, or dormant. Its antonym would therefore be active, as it represents the opposite state of rest or inactivity.

Opposite words: Active, Vigorous, Agitated, Operated, Lively.

The word "hirsute" means hairy or shaggy. The antonym (opposite) of "hirsute" is bald, which means lacking hair.

Opposite words: Bald, Smooth, Glabrous, Bare, Shaven, Depilated.

"Parallelism" refers to things being aligned in a similar direction, often in a balanced or consistent way. The opposite of this would be "divergence," which refers to things moving or developing in different directions.

Opposite words: Disparity, Divergence, Incompatibility, Dichotomy, Polarity.