Lewis & Short

gĕmellar, āris, n. [gemellus], a vessel for holding oil (very rare), Col. 12, 52, 10.
Also gĕmellārĭa, ae, f., Aug. ap. Psa. 136 med.; and gĕmellārĭum, i, n., id. ap. Psa. 80, 1 al.