Pos·set, v. t. [imp. & p. p. Posseted; p. pr. & vb. n. Posseting.] 1. To curdle; to turn, as milk; to coagulate; as, to posset the blood. [Obs.] 2. To treat with possets; to pamper. [R.] “She was cosseted and posseted.” ◄ ►