Aduno, adúnas, pen. longa, adunâre. Plin. To gather or heape togither.
Lewis and Short: Latin dictionary
ăd-ūno, āvi, ātum, 1, v. a., to make one, to unite (in Just. several times, elsewhere rare, except in the Chr. fathers): cum adunata omnis classis esset, Just. 2, 12; so 7, 1; 15, 4; Pall. 3, 29; 4, 10; Lact. Opif. D. 17 al. (Non. reads also, in Cic. Off. 3, 8, 35, erroneously, adunatam for adjunctam, B. and K.).