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know one's onions

ADJECTIVE

able

Synonyms

STRONGEST

adept apt capable competent proficient skilled

STRONG

accomplished adroit effective experienced practiced qualified skillful talented

WEAK

clever facile know the ropes masterful masterly savvy smart trained up to snuff

Antonyms

STRONGEST

incapable incompetent ineffective

STRONG

inept poor weak

WEAK

ignorant impotent useless