Lewis Short
(verb) : ad-densĕo, ēre, and ăd-denso, āre (cf. Wagner ad Verg. G. 1, 248), 2 and 1
* To make close, compact (very rare): extremi addensent acies,Verg. A. 10, 432 Rib.—In pass., of water, to become thick, to thicken: aquam radice ea addita addensari,Plin. 20, 21, 84, § 230.
Charlton T. Lewis, Charles Short, A Latin Dictionary