The origin is uncertain. Clearly related is Arb. miǯdaḥ- ‘seashore’, but one may doubt that this extremely rare and isolated word is autochtonous in Arabic (Kogan 2015: 553)
The same
meaning for this root is attested in the Arabic dialects of Southern Arabia
(Landberg 1901:531, GD 264, Piamenta 61), but it is hard to say whether the
MSA terms are borrowed from Arabic or rather the Arabic ones are due to substratum/
adstratum influence of MSA (Kogan 2015: 554)
The origin is unknown. Of some interest may be Tna. guḥo ‘cave, crevice or hollow in a mountainside’.
For ǯaḥi ‘sol’ in Dathina v. GD 266 (due to MSA influence?)
The origin of Proto-MSA *glw ‘to be ill’ is unknown. Assuming that the original meaning of the root is “to be hot”, one might tentatively compare Arb. ǯlw ‘to be clear, bright’ (Kogan 2015:554)