ex·haus·tive \-stiv, -tēv also -təv\adjective : serving or tending to exhaust : testing all possibilities or considering all the elements : thorough < an exhaustive investigation > < exhaustive list > : complete < exhaustive methylation > • ex·haus·tive·ly\-tə̇vlē, -li\adverb • ex·haus·tive·ness\-tivnə̇s, -tēv- also -təv-\noun-es