jac·tance \ˈjaktən(t)s\noun orjac·tan·cy\-nsē\ (pluraljactancesorjactancies) Etymology: Middle French & Latin; Middle French jactance, from Latin jactantia, from jactant-, jactans (present participle of jactare to throw, shake, speak out, boast) + -ia -y — more at jet : vainglorious boasting < jactance, vanity, peculation to the ruin of 20 years' labor — Ezra Pound >