FATUITY Meaning of FATUITY in English [fa.tu.ity] n, pl -ities [MF fatuite foolishness, fr. L fatuitat-, fatuitas, fr. fatuus] (1538) 1 a: something foolish or stupid b: stupidity, foolishness 2. archaic: imbecility, dementia Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012