undecomˈpounded,ppl.a. (un-1 8.) 1795Phil.Trans. LXXXV. 340 Wrought iron is to be considered as a simple or undecompounded body.1804Edin.Rev. IV. 126 A number of substances which are still undecompounded.1843Civil Eng. & Arch.Jrnl. VI. 420/1 The earths being classed as undecompounded bodies.