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 PDF — $25 TOEFL PDF — $25 ← hew hiatus → Study tips featuring "heyday" TOEFL Academic Vocabulary: Study by Topic Related words GRE awe GRE smithereens GRE abacus SAT abase GRE abash GRE abate GRE abbreviate GRE abbreviation SAT abdicate SAT abdomen GRE abduct GRE aberrant