Definition of Existentialist 1. Relating to or involving existentialism Adjective 2. A philosopher who emphasizes freedom of choice and personal responsibility but who regards human existence in a hostile universe as unexplainable Noun Synonyms for word "existentialist" Semanticaly linked words with "existentialist" Hyponims for word "existentialist" Lexical Analysis for "existentialist" existentialism (philosophy) a 20th-century philosophical movement chiefly in Europe; assumes that people are entirely free and thus responsible for what they make of themselves existentialism (philosophy) a 20th-century philosophical movement chiefly in Europe; assumes that people are entirely free and thus responsible for what they make of themselves has derived form exist has derived form existential etymologically related exist etymologically related existence etymologically related existential etymologically related existentialism etymologically related existentialistically etymologically related existentially is derived from existentialists