Aletheia

Aletheia is the Greek word for "truth", and like the English word implies sincerity as well as factuality or reality. The literal meaning of the word is "the state of not being hidden; the state of being evident".
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Aletheia (Greek) [from a not + lethein to be hid] Truth, as opposed to a lie or to unreality. Also a sapphire ornament worn by the Egyptian high priest (Diodorus and Aelianus).