Definition 1: Lighthearted, lacking care or concern, blithely indifferent or nonchalant.

Usage 1: Careful of the spelling: an "a" and not an "e" in the suffix. The noun is "insouciance."

Suggested usage: Insouciance is often associated with youth, though it follows many of us into adulthood. If your child is not quite mature enough to drive the family car, remind them, "Youthful insouciance is not a good recommendation for driving the new Mercedes." But save this word for romantic moments when you wish to intimate the ultimate in relaxation: "Her slender fingers touched the brim of her hat with an insouciant gesture that both engaged and disarmed him."

Etymology: Shamelessly copied from the French insouciant "lacking care or concern," a negated participle comprising " in- "not" + (se) soucier "care." French "soucier" is not a sauce but a reduction nonetheless, via elision (see our Word of the Day archive), of Latin sollicitare "to vex" from sollus "whole, entire" + citus past participle of cire "to set in motion." The root of "sollus" also appears in salvus "health" that turns up in English "salvation", "salutory," "safe," and "save." "Cire" comes from the same root that underlies Greek kin-ein "to move" found in English borrowings"cinema" and "kinetic." (We are not in the least insouciant of the contribution of James Kirtley and Don Carroll in suggesting today's word.)