From Longman Dictionary of Contemporary Englishunderarmun‧der‧arm1 /ˈʌndərɑːm $ -ɑːrm/ adverb DS British English if you throw a ball underarm, you throw it without moving your arm above your shoulder OPP overarm SYN underhand American English
Examples from the Corpus
underarm• He was also the only player known to throw underarm.underarmunderarm2 adjective 1 [only before noun] relating to or used on your armpits underarm hair underarm deodorants2 an underarm throw is one where you throw a ball without moving your arm above your shoulder OPP overarm underarm bowlingExamples from the Corpus
underarm• underarm deodorantunderarmunderarm3 noun [countable] the hollow area under your arm, where it joins your body SYN armpitExamples from the Corpus
underarm• She shaved her legs and underarms, and shampooed her hair. 