“… kotel הַכֹּתֶל הַמַּעֲרָבִי   appears only once (Shir Hashirim 2:9). Kotel likely has Aramaic origins, and Klein points out that the Aramaic cognate כתלא kutla is probably a loan word from the Akkadian kutallu – “back side”. It was used frequently in rabbinic Hebrew, but in modern Hebrew it’s generally reserved to describe the western retaining wall of the Temple Mount – the kotel hamaaravi הכותל המערבי.” Balashon