/ ˌɪnfɪnɪˈtesɪml; NAmE / adjective
( formal ) extremely small
SYN tiny :
infinitesimal traces of poison
an infinitesimal risk
► in·fini·tesi·mal·ly / -məli; NAmE / adverb
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WORD ORIGIN
mid 17th cent.: from modern Latin infinitesimus , from Latin infinitus , from in- not + finitus finished, finite, past participle of finire , from finis end, on the pattern of centesimal .