GRE TOEFL optimum Definition The most favorable or ideal condition or level. Example "This plant grows at its optimum in moist, shaded soil." Sign in to save GRE PDF — $25 TOEFL PDF — $25 ← optimistic option → Study tips featuring "optimum" 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