No feminine formation from PS *ṯawr- ‘bull, ox’ is attested outside PArm. *ṯawr-at-. The only exception is Arb. ṯawrat-, but this rare word is certainly no basic designation of “cow” in Arabic (in TA 10 338, only one verse by al-Aḫṭal is adduced as an illustration, which may testify to the restricted use of this lexeme).
Attested from Official Aramaic onwards. The only, semantically very remote WS cognate to the Aramaic verb is Arb. wmˀ ‘to make a sign’. Conversely, the Akkadian verb wamāˀu ‘to swear’ is attested as early as the Sargonic royal inscriptions, so the possibility of an early loan cannot be ruled out (Kogan–Krebernik 2021a:389).