Arabic

labab- - the top of the chest or chest from which descends a necklace or other neck adornment; chest strap (of horse etc.) (BK 2 955; WKAS II 83)

*labb(-at)-, *lab(y)-ān- - (animal's) body from neck to rump (SED I No. 173)

Meaning somewhat diffuse (originally may denote trunk as a whole). Semantically and phonetically (a vs. i) rather to be separated from *libb- ‘heart’.