In Siwi, the situation is slightly different. Unlike the hesitations and disagreements of Korandje speakers asked about this subject, Siwi speakers asked to translate Arabic jism "body" confidently reply aglim, and early wordlists confirm that they have been doing so for over a century. However, if you ask them to translate aglim, they equally consistently reply with Arabic jild "skin". A person or animal has an aglim, but so does a potato, and its aglim can be peeled off. To further complicate the semantic field in question, ilem also translates as jild "skin", but refers to a piece of skin rather than to the whole: kteṛṭiyya aksum ɣair ilem "You have brought me meat that is nothing but skin"; ilem en ṭad yekkes "Some skin came off his finger". This renders the interpretation of aglim questionable. Does it have two distinct meanings, "body" and "(whole) skin"? Or does it just mean "(whole) skin", and refer to the body only as the volume encompassed by the skin?
Thinking out the question here makes it obvious what I should try to elicit next time the occasion arises: how to say "The human body is covered with skin" or "A snake sheds its skin many times, but always has the same body". Any other suggestions for contexts that clearly bring out the relevant differences in meaning?
(I should mention that this question was inspired by a recent talk by Mustapha El Adak of the University of Oujda, arguing that all non-borrowed Berber words for "body" either include non-physical aspects of the person or relate specifically to a particular aspect of the body rather than referring uniformly to the whole.)