An acinus (/ˈæsɪnəs/; plural, acini; adjective, acinar /ˈæsɪnər/ or acinous) refers to any cluster of cells that resembles a many-lobed "berry," such as a raspberry (acinus is Latin for "berry"). The berry-shaped termination of an exocrine gland, where the secretion is produced, is acinar in form, as is the alveolar sac containing multiple alveoli in the lungs.