köken: Attested late; first attestation may be Mullā Tughrā (died 1667). From a suffixed form of Proto-Iranian *ák- (“bad”), related to Proto-Indo-European *ákas (“bad”). Compare Avestan 𐬀𐬑𐬙𐬌 (axti, “pain, suffering”) and Sanskrit अक (aka, “pain”).
köken: Borrowed from Middle French fronce, from Old French fronce, from Frankish *hrunkja (“wrinkle”) from Proto-Germanic *hrunkijō, *hrunkitō (“fold, wrinkle”), from Proto-Indo-European *sker- (“to turn, bend”). The semantic narrowing to frowns on the forehead may be influenced by unrelated Latin frōns.