The Collaborative International Dictionary
Papain \Pa*pa"in\, n. [From Papaw.] (Physiol. Chem.) A proteolytic ferment, like trypsin, present in the juice of the green fruit of the papaw ( Carica Papaya) of tropical America.
papaya \pa*pa"ya\, n. [Prob. from the native name in the West Indies; cf. Sp. papayo papaw, papaya the fruit of the papaw.]
(Bot.) A tree ( Carica Papaya) of tropical America, belonging to the order Passiflore[ae]; called also papaw and pawpaw. It has a soft, spongy stem, eighteen or twenty feet high, crowned with a tuft of large, long-stalked, palmately lobed leaves. The milky juice of the plant is said to have the property of making meat tender.
The fruit of the papaya tree; it is a dull orange-colored, melon-shaped fruit, which is eaten both raw and cooked or pickled. The fruit contains papain, a protease.