Lewis & Short

helvĕŏlus, a, um, adj. [helvus], pale yellow, yellowish: vinum, a particular kind of wine (cf. helvenacus and helvolus), Cato, R. R. 6, 4; 24, 2 (quoted, Plin. 14, 4, 5, § 46, in the form helvinum vinum). Also in the form helvolus, a, um: uvae, Col. 3, 2, 23; Plin. 14, 2, 4, § 29.