c. 1300, "of or concerning the spirit" (especially in religious aspects), from Old French spirituel, esperituel (12c.) or directly from a Medieval Latin ecclesiastical use of Latin spiritualis "of or pertaining to breath, breathing, wind, or air; pertaining to spirit," from spiritus "of breathing, of the spirit" (see spirit (n.)). Meaning "of or concerning the church" is attested from mid-14c. Related: Spiritually. An Old English word for "spiritual" was godcundlic.
In avibus intellige studia spiritualia, in animalibus exercitia corporalia [Richard of St. Victoror (1110-1173): "Watch birds to understand how spiritual things move, animals to understand physical motion." - E.P.]