Noun. 1. basin-a bowl-shaped vessel; usually used for holding food or liquids; she mixed the dough in a large basin. aspersorium-the basin or other vessel that holds holy water in Roman Catholic Churches.baptismal font, baptistery, baptistry, font-bowl for baptismal water.asin-a bathroom sink that is permanently installed and connected to a water supply and drainpipe; where you can wash your hands and face; he ran some water in the basin and splashed it on his face. washbasin, washbowl, washstand, lavatory.