Lewis Short
lăcūna | lŭcūna | lăcūnā-tūra (noun F) : (collateral form ; cf. Lachm. ad Lucr. vol. 2, p. 205; , App. Flor. 15, p. 351, 2 Hildebrand;
* V.infra), , f.lacus, a ditch, pit, hole; esp. a place where water collects, a pool, pond.
* Lit. (mostly poet.): lacuna, id est aquae collectio, a lacu derivatur, quam alii lamam, alii lustrum dicunt, Paul. ex Fest. p. 117 Müll.: vastae,Lucr. 6, 552: vastae Orci,id. 1, 116; 6, 538: cavae,Verg. G. 1, 117; 3, 365.—Poet.: salsae,i. e. the sea,Lucr. 5, 794; 3, 1044; also, Neptuniae,Auct. Her. 4, 10, 15: caecas lustravit luce lacunas,Cic. Arat. 431.
* In gen., a hollow, cavity, opening, chasm, cleft: cum supercilia cana, et sub ea lacunae, dicunt, eum equum habere annos sedecim,Varr. R. R. 2, 7, 3; 1, 29, 3; cf.: atque lacunarum fuerant vestigia cuique,Lucr. 5, 1261; Vitr. 7, 1, 4: labrum superius sub ipsa medietate narium lacuna quadam levi, quasi valle, signavit deus,Lact. Op. D. 10: genae teretes ac medio mento lacuna,a dimple,App. Flor. p. 351 (Hildebr., lacunatura).
* Trop., a gap, void, defect, want, loss (rare but class.): est, qui expleas duplicem istam lacunam,to fill up the double void,Varr. R. R. 2, 1, 28: ut illam lacunam rei familiaris expleant,Cic. Verr. 2, 2, 55, § 138: lacuna in auro,id. Att. 12, 6, 1: illa labes et quasi lacuna famae,Gell. 1, 3, 23.
Charlton T. Lewis, Charles Short, A Latin Dictionary