The guar or cluster bean, with the botanical name Cyamopsis tetragonoloba, is an annual legume and the source of guar gum. It is also known as gavar, gawar, or guvar bean.

The origin of Cyamopsis tetragonoloba is unknown, since it has never been found in the wild. It is assumed to have developed from the African species Cyamopsis senegalensis. It was further domesticated in South Asia, where it has been cultivated for centuries. Guar grows well in semiarid areas, but frequent rainfall is necessary.

This legume is a valuable plant in a crop rotation cycle, as it lives in symbiosis with nitrogen-fixing bacteria. Agriculturists in semi-arid regions of Rajasthan follow crop-rotation and use guar to replenish the soil with essential fertilizers and nitrogen fixation, before the next crop. Guar has many functions for human and animal nutrition, but the gelling agent in its seeds (guar gum) is the most important use. Demand is rising due to the use of guar gum in hydraulic fracturing (oil shale gas).. It is also a major ingredient of the toy slime. About 80% of world production occurs in India, but due to strong demand, the plant is being introduced elsewhere.