PS

*gapp-, *ˀa-gapp- - wing (SED I No. 88)

There is a trend to compare this root with Sem. *gd/ḏp ‘to fly’ > *gadp- ‘wing’ implying a secondary formation with loss of *-d-, which is unlikely

Akkadian
gappu - wing (CAD K 185, AHw. 281)
Var. agappu.
Identified by CAD with kappu, but treated as a separate entry in AHw, which seems right in view of the comparative data; note that in AHw agappu is also treated as a separate gloss independent of gappu (AHw 15).
Hebrew
gap - the long portion of the wing; arms, shoulders (Jastrow 262)
Demotic Aramaic
gp - wing (DNWSI 1255)
Jewish Babylonian Aramaic
gappā - wing; winged animal (Jastrow 262, DJBA 297a)
gp ‘wing’ [Sok. 134]
Syriac
geppā - wing; arm; fin; ell, fathom (LSyr. 128, SL 253)
Mandaic
gapa - wing (MD 78)
Arabic
ǯff - agiter les ailes (se dit d'un oiseau qui couve) (to wave wings (said of a brooding bird) (BK 1 302)
Arabic
ǯfǯf - s'agiter, hérisser ses plumes et lever les ailes, comme fait un oiseau qui couve ses oeufs, à l'approche d'un ennemi (to flutter, bristle its feathers and lift its wings, like a bird that incubates its eggs, when an enemy approaches) (BK 1 303)
Tigre
gəfa - long train (of dress) (WTS 605)
May be a meaning shift from ‘wing’