Antonyms

Bolster means to support, strengthen, or reinforce something. Decrease (as in to reduce support) works as the opposite in this context - to weaken or reduce the support for something. The other options are less directly opposite to bolster's meaning of reinforcement.

Pristine means in original, clean, and unspoiled condition. Contaminated is the direct opposite - polluted, made impure, or dirtied. The other options describe moral qualities or attractiveness, not physical condition.

Instinct refers to innate, natural behavior or responses (not learned). Learned response is the direct opposite - behavior acquired through training and experience rather than being inborn. The other options describe psychological concepts unrelated to the nature of behavioral origins.

Alleviate means to make something less severe, painful, or burdensome - to relieve. Exacerbate means to make worse, more severe, or more intense - directly opposite in effect. The other options describe different actions not specifically about making conditions worse.

Proliferate means to increase rapidly in number, to multiply, or grow abundantly. Diminish means to become smaller, fewer, or less - directly opposite in numerical direction. While 'restrict' could also be opposite, diminish more directly counters the numerical increase aspect of proliferation.

 Sensation refers to the senses so in this sense, it refers to a feeling of type which is tangible. The opposite of this is partial dullness.

 Dessicate means to remove water or dehydrate so that what is left is a powder.

Affable means friendly, good-natured, and easy to talk to. Irascible means easily provoked to anger, irritable, or quick-tempered - directly opposite in social disposition. The other options describe different negative traits not specifically opposing friendliness.

Inadvertent means unintentional or accidental. Intentional means done on purpose, which is the direct opposite. The other options do not convey the opposite meaning.

Inundate means to flood, overwhelm, or cover with water. Drain means to remove liquid, which is the direct opposite action. The other options do not convey removing liquid.

Fatuity means foolishness, stupidity, or silliness. Sagacity means wisdom and sound judgment, which is the direct opposite quality.

Sate means to satisfy fully, especially with food or drink. Starve means to deprive of food, which is the direct opposite state.

Quack refers to a fraudulent or pretentious practitioner, especially in medicine. Honest practitioner is the direct opposite - someone legitimate and genuine.