early 15c., "angry; emotional, subject to emotions, exhibiting or expressing passion in any sense," from Medieval Latin passionatus "affected with passion," from Latin passio (genitive passionis) "suffering, enduring" (see passion). Specific sense of "amorous" is attested from 1580s. Related: Passionately; passionateness. Middle English also had passional "pertaining to the feelings" (mid-15c., from Medieval Latin passionalis).
