The etymology of Proto-MSA *ˁar ‘but’ is uncertain. A cognate relationship with Arb. γayr- is rather attractive, but ˁ instead of γ is hard to explain. (Kogan 2015:549)
Proto-MSA
*ˁ/ˀardīb - nape of the neck and the top of the shoulders
(SED I 44, Kogan 2015:549–550)