castaway UK /ˈkɑːstəweɪ/US /ˈkæs.tə.weɪ/adjective 3noun 3forms 1 adjective3 •Cast adrift or ashore; marooned.After the mutiny, the castaway ship's officers suffered a month at sea in the lifeboat. •Shipwrecked.The storm left them castaway on an uninhabited island. •Cast out; rejected or excluded from a group. noun3 •A shipwrecked sailor.Robinson Crusoe was a famous fictional castaway. •A discarded person or thing.This old coat was a castaway in someone's trash. •An outcast; someone cast out of a group or society.These homeless people are society's castaways. formscastaways