PS

*γa/ub(a)b- - bosom, chest; dewlap (SED I No. 104)

Jewish Palestinian Aramaic
ˁwb - breast (DJPA 397)
det. ˁubbā
Jewish Babylonian Aramaic
ˁubbā - bosom, lap (Jastrow 1046, DJBA 84b)
Syriac
ˁubbā - bosom (LSyr. 503, SL 1076)
Mandaic
ˁumba - bosom (MD 344)
-m- may imply the protoform *γa/umb-
Arabic
γabab- - hanging flesh under the chin (of some animals), dewlap (of oxen), beard (of cock), throat (of humans) (BK 2 429)
Arabic
γabγab- - dewlap, beard, throat (BK 2 433)
a reduplicated stem
Amharic
əmbiya - chest (of an equine or other animal not considered licit to eat) (AED 1330)
-bb- > -mb- is not unfrequent in Amh. The protoform may be *γa/umb-