8 letters · 10 points in Scrabble
noun a disloyal person who betrays or deserts his cause or religion or political party or friend etc.
adjective not faithful to religion or party or cause
originFrom Late Latin apostata, from Ancient Greek ἀποστάτης (apostátēs, “rebel”), from ἀφίστημι (aphístēmi, “to withdraw, revolt”), from ἀπό (apó, “from”) + ἵστημι (hístēmi, “to stand”).
Etymology from Wiktionary, CC BY-SA 3.0