late 14c., spiritualite, "the clergy," also "ecclesiastical property; things pertaining to the Church," from Anglo-French spiritualite, Old French espiritualite, and directly from Late Latin spiritualitatem (nominative spiritualitas), from Latin spiritualis (see spiritual). Meaning "quality of being spiritual" is from c. 1500; seldom-used sense of "fact or condition of being a spirit" is from 1680s. Also in early use spiritualty (late 14c.).
English is blessed with multiple variant forms of many words. But it has made scant use of them; for every pair historic/historical; realty/reality, or luxuriant/luxurious there is a spiritualty/spirituality or a specialty/speciality, with two distinct forms, two senses requiring differentiation, hundreds of years gone by, and but little progress made in in sorting them out.