What's the "een" in Halloween?
late 14c., "condition of enjoyment," from Old French plesir, also plaisir "enjoyment, delight, desire, will" (12c.), from noun use of infinitive plaisir (v.) "to please," from Latin placere "to please, give pleasure, be approved" (see please (v.)). Ending altered in English 14c. by influence of words in -ure (measure, etc.). Meaning "sensual enjoyment as the chief object of life" is attested from 1520s.
1530s, "to take pleasure in;" 1550s as "give pleasure to," from pleasure (n.). Sexual sense by 1610s. Related: Pleasured; pleasuring.