Arabic

lubbat- - the upper chest that meets the collarbone (BK 2 955)

The suffix -ān­ in labān-. 

PS
*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’.