itsy-bitsy /ˈɪtsi ˈbɪtsi/adjective 1noun 1forms 5 adjective1 •(informal, humorous) Very small; minuscule.The itsy-bitsy spider climbed up the water spout.She wore an itsy-bitsy teeny-weeny yellow polka-dot bikini. noun[in the plural]1 •A very small thing; something tiny or insignificant. formsitsy-bitsies · itsy bitsier · itsy-bitsier · itsy bitsiest · itsy-bitsiest