GRE TOEFL heyday Definition The period of greatest success, popularity, or activity. Example "The 1980s were the heyday of rock music." Sign in to save GRE Quiz → TOEFL Quiz → ← hew hiatus → Study tips featuring "heyday" Write GRE Words Into Your Own Sentences TOEFL Academic Vocabulary: Study by Topic Related words GRE swill GRE taper GRE testy GRE abacus SAT abase GRE abash GRE abate GRE abbreviate GRE abbreviation SAT abdicate SAT abdomen GRE abduct