13th cent. A learned borrowing from Latin blasphemare 'id.' The native word is lastimar. Borrowed from Greek βλασφημεῖν (blasphemeîn) "to blaspheme," originally "to slander."
Of unknown origin. The first element is mysterious; the second element is probably from φήμη (phéme) "reputation," "voice." From late Proto-Indo-European *bheh2-m̥h2- "reputation," also whence the word fama.