Lewis & Short

mātrĭcīda (scanned matrĭcĭda, Sid. Carm. 5, 291), ae, comm. [mater-caedo], a mother’s murderer, a matricide (rare but class.): quem scribis certissimum matricidam, Cic. Q. Fr. 1, 2, 2; Nep. Alc. 6, 2: cantavit Oresten matricidam, Suet. Ner. 21.
In tmesi: matrique cida Nero, Aus. de XII. Caes. 35 (al. matrīcīda Nero).