SAT GRE TOEFL momentous Definition Of great importance or significance. Example "The discovery of penicillin was a momentous event in medical history." Sign in to save SAT PDF — $25 GRE PDF — $25 TOEFL PDF — $25 ← momentary momentum → Study tips featuring "momentous" TOEFL Academic Vocabulary: Study by Topic How Context Clues Save You on the SAT Related words SAT antonym SAT abase SAT abdicate SAT abdomen SAT abduction SAT abet SAT abeyance SAT abject SAT abjure SAT ablution SAT abnegate SAT abnormal