† deconˈcert,v.Obs.rare. [a. F. déconcerter (16th c.), f.dé-, des- (de- I. 6) + concerter.] trans. To put out of concert or agreement, disarrange; = disconcert 1. 1715M. Davies Athen. Brit. I. 322 A more heterogene Metamorphosis, capable of deconcerting the closest Union and Interest.