An Etymological Dictionary of Astronomy and Astrophysics

Of a surface, curving inward.

Etymology (EN): From L. concavus “hollow,” from → com- intensive prefix + cavus “hollow;” PIE base *keu- “a swelling, arch, cavity.”

Etymology (PE): Kâv “hollow,” verb kâvidan (kâftan) “to dig; to examine, investigate,” cf. L. cavus “hollow” (E. derivatives: cavity, concave, cave, excavate), Gk. koilos “hollow,” Armenian sor; PIE *kowos “hollow.”