Invalid1  —n. Person enfeebled or disabled by illness or injury. —attrib. Adj. 1 of or for invalids. 2 sick, disabled. —v. (-d-) 1 (often foll. By out etc.) Remove (an invalid) from active service. 2 (usu. In passive) disable (a person) by illness.  invalidism n. Invalidityn. [latin: related to *in-1]