casualty (n.)

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.

c. 1500, "punishment," from Old French penalite and directly from Medieval Latin penalitatem (nominative penalitas), from Latin poenalis "pertaining to punishment" (see penal). Specifically as "the punishment laid out by law or judicial decision for a violation of the law" is by 1510s (also later for non-fulfillment or violation of an obligation or agreement). The sporting sense of "disadvantage imposed on a competitor for a breach of the rules" is by 1885; the ice hockey penalty box is attested by 1931.