"state of being casual," 1730, from casual (adj.) + -ness.
Entries linking to casualness
casual adj.
late 14c., casuel, "subject to or produced by chance," from Old French casuel (15c.), from Late Latin casualis "by chance," from Latin casus "chance, occasion, opportunity; accident, event" (see case (n.1)).
Of persons, in the sense of "not to be depended on, unmethodical," it is attested from 1883 (from the notion of "without regularity," hence "uncertain, unpredictable"); the meaning "showing lack of interest" is from 1916. Of clothes, "informal," from 1891. Related: Casually.
-ness
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).