deep (subs.) Copy link Outline 1. altum2. prŏfundum (rare)3. pontus (the deep sea) • deep (subs.): 1. altum: tossed on the d., jactatus alto, Virg. 2. prŏfundum (rare): the father of the d. (Neptune), pater profundi., Val. Fl. 3. pontus (the deep sea): Virg. Ov v. sea.