spiritual (adj.)
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.
spiritual (n.)
"African-American religious song," 1866, from spiritual (adj.). Earlier "a spiritual thing" (1660s).