Lewis & Short

pŏēma, ătis (gen. plur. poëmatorum, Afran. ap. Non. 493, 9; cf. Charis. p. 114 P.: poëmatum, Suet. Gram. 23; Spart. Hadr. 14; dat. and abl. plur. usually poëmatis, Cic. Off. 3, 3, 15; Plaut. As. 1, 3, 22; Auct. Her. 4, 2, 3; but also poëmatibus, Suet. Tit. 3; App. Mag. 5), n., = ποίημα, a composition in verse, a poem (freq. and class.; syn. carmen): pars est parva poëma, proinde ut epistola quaevis. Illa poësis opus totum, ut tota Ilias una Est θέσις, annalesque Enni: atque istoc opus unum Est majus multo quam quod dixi ante poëma, Lucil. ap. Non. 428, 12 sq.; cf.: poëma est λέξις εὔρυθμος, id est verba plura modice in quandam conjecta formam. Itaque etiam distichon epigrammation vocant poëma. Poësis est perpetuum argumentum e rhythmis, ut Ilias Homeri et Annales Ennii, Varr. ap. Non. 428, 19 sq.
Plur.: poëmata (opp. oratio), poetry, Cic. Or. 21, 70.
So of some verses of a poem: o poëma tenerum et moratum atque molle! Cic. Div. 1, 31, 66; and of a short poem, Cat. 50, 16, 1. But this distinction is not observed even by Ennius, and poëma was the name in the class. period for every kind of poem: latos per populos terrasque poëmata nostra clara cluebunt, Enn. ap. Prob. p. 1401 P. (Ann. v. 3 Vahl.): poëma facere, Cic. Ac. 1, 3, 9: poëma ad Caesarem quod composueram, incidi, id. Q. Fr. 3, 1, 4, § 11: Graecum condere, id. Att. 1, 16, 15: pangere, Hor. Ep. 1, 18, 40; id. A. P. 416: scribere, id. Ep. 2, 1, 117: egregium, Cic. de Or. 1, 50, 217: poëma festivum, concinnum, elegans, id. Pis. 29, 70: si poëma loquens pictura est, pictura tacitum poëma debet esse, Auct. Her. 4, 28, 39: ridenda poëmata malo, quam te, Juv. 10, 124.