why

1 something (as a belief) that serves as the basis for another thing asked the whys behind the surprising decision Synonyms account, authority, grounds, motive, subject, wherefore, reasonRelated Words antecedent, cause, consideration, impetus, incentive, inspiration, instigation, occasion, stimulus

2 something hard to understand or explain how one decides that a certain he or she is “the one” is one of the great whys of life Synonyms closed book, conundrum, enigma, head-scratcher, mystification, puzzle, puzzlement, riddle, secretRelated Words brainteaser, case, challenge, knot, matter, perplexity, poser, problem, stumper, trouble