Gregarious describes a person who enjoys company, crowds, and socializing; in everyday speech it means outgoing or sociable. The word comes from the Latin grex, meaning flock or herd.
In biology it describes animals that live or travel in herds, flocks, or packs, such as sheep or starlings, and in botany it describes plants that grow in open clusters or colonies.
Source: gregarious, Wiktionary
Image: Flock of sheep by Keith Weller, public domain, via Wikimedia Commons.