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. 1400, "office or position of a sovereign, royal power or authority," also "magnificence," from or modeled on Old French roialte (12c., Modern French royauté), from Vulgar Latin *regalitatem (nominative *regalitas), from Latin regalis "royal, kingly; of or belonging to a king, worthy of a king" (see royal (adj.)).

The meaning "royal persons collectively" is from late 15c. From the notion of prerogatives of a sovereign the sense expanded to "prerogatives or rights granted by a sovereign to an individual or corporation" (late 15c.). From that evolved more general senses, such as "payment to a landowner for use of a mine" (1839), and ultimately "payment to an author, composer, etc." for sale or use of his or her work (1857). Compare realty.