Synonyms and related words :
absurd idea, boutade, brainstorm, capriccio, caprice, conceit, crank, craze, crotchet, fad, fancy, fantastic notion, fantasy, flimflam, fool notion, freak, freakish inspiration, harebrained idea, humor, kink, maggot, megrim, notion, passing fancy, quirk, toy, vagary, whim, whim-wham, whimsy,