Variant of Alethea, from Greek 'aletheia' meaning truth or sincerity.
Alethia is a variant spelling of Alethea, a name of pure Greek philosophical pedigree: it derives directly from aletheia, meaning "truth" or, more precisely, "unconcealment" — the state of things being revealed and unhidden. In ancient Greek philosophy, aletheia was not merely factual accuracy but a deeper kind of disclosure, the bringing of what is real into the light of understanding. Martin Heidegger famously placed aletheia at the center of his philosophical project, arguing that the ancient Greeks understood truth not as correctness but as a kind of unconcealing of being — lending the name an unexpected twentieth-century philosophical currency.
As a given name, Alethea and its variant Alethia appeared in England during the Renaissance, when classical learning enjoyed a revival that sent humanists reaching for Greek vocabulary to name their children. The Countess of Arundel, Aletheia Howard, was a notable seventeenth-century bearer — a great patron of the arts who assembled one of the finest art collections in Stuart England and whose portrait was painted by Rubens. The name carried an aura of learning and virtue appropriate to that humanist moment.
Alethia (with the -ia ending) has the feel of a name rescued from a long sleep, rare enough to surprise but classical enough to carry authority. It sits near Althea and Alethea in sound and spirit but has its own distinct visual identity. The name appeals to parents who love names that mean something precise and profound — who want a daughter's name to be not merely beautiful but philosophically true, a small act of naming that carries the weight of an ancient concept about the nature of reality itself.