Ephemeral means lasting a very short time. Permanent means lasting indefinitely, making it the antonym.

Prolific means producing much fruit, foliage, or many offspring; fertile and productive. Barren is the opposite.

Vigorous means forceful and energetic. Weak, sluggish, and lethargic all represent opposite meanings.

Abscond means to leave secretly. Surrender, meaning to give oneself up, is the nearest antonym.

Candid means frank and honest. Evasive means avoiding direct answers, making it the antonym.

Lucid means clear and easy to understand. Obscure means unclear and difficult to understand, the opposite.

Convoluted means complicated and difficult to follow. Straightforward means simple and direct, the opposite.

Ambiguous means unclear or capable of multiple interpretations. Unequivocal means clear and unambiguous, the opposite.

Frivolous means not serious or trivial. Serious means grave and important, making it the antonym.

Gregarious means fond of being in crowds or groups. Solitary means alone or preferring to be alone, the opposite.