The root of the word may be related, with metathesis, to Akk. dagālu 'look' and the lexemes listed under the entry.
Dissimilation < *maˁām(-at)- < *maˁmaˁ(-at)-? (can n- < *m- be influenced by contamination with nuḫḫ-, naḫāḫat- ‘bone marrow’ [ibid. 1219]?). Phonetically quiestionable.