Gac, from the Vietnamese gấc (pronounced [ɣək˦˥]), scientific name Momordica cochinchinensis, is a species of plant in the melon and cucumber family Cucurbitaceae which is native to countries throughout Southeast Asia and to Queensland, Australia.

Momordica cochinchinensis is a perennial tendril climber which may reach up to 15 metres (50 feet) long and a stem diameter up to four centimetres (1+1⁄2 inches).

[2][3][4][5][6] They are initially green but turn a deep orange/red at maturity, and they contain numerous irregularly-shaped brown or grey seeds which are enclosed in a bright red aril.

[14] The genus name Momordica is derived from the Latin word mordeo meaning to bite, a reference to the seeds' appearance as though chewed.

[7] The species epithet cochinchinensis means "from Cochinchina", the region in the southern part of Vietnam where the plant was first observed by Loureiro.

[7][15] As this plant is native to many countries throughout the Asia-Pacific region, it has a diverse number of common names including: bhat kerala (Assamese), mu bie gua, mu bie zi and teng tong (Chinese), balsam pear, Chinese cucumber, and giant spiny gourd (English), kakur, kantola and kakrol (Hindi), tepurang (Indonesian), mokube tsushi (Japanese), makkao (Khmer), khaawz (Laotian), pupia, teruah and torobuk (Malay), jhuse karelaa (Nepalese), pakurebu (Sulawesi), buyok buyok (Tagalog), phak khao (Thai), and gac (Vietnamese).

[18] If propagating from vines, farmers make diagonal cut (around 15–20 cm or 6–8 in long and 3–6 mm or 1⁄8–1⁄4 in wide), then root the tubers in water or well-aerated, moist potting media before planting.