Third-person singular or plural of 'fain,' meaning to be glad, willing, or pleased about something.
From Old English 'fægnan,' related to the adjective 'fægn' (joyful). The verb form is archaic in modern English but reflects how older English speakers could express gladness as an active state.
This verb form is almost extinct in everyday speech, but it's incredibly useful for understanding old poetry and literature—when someone 'fains,' they're expressing a kind of joyful willingness that modern English requires multiple words to capture.
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