From m-(noun-forming prefix) + *ms(“to twist, to weave”) with regular dissimilation of m- to n- before a labial consonant; for the stem, itself unattested, compare the extended verb msn(“to twist, to weave”).[1]
Archaic or greatly restricted in usage by Middle Egyptian. The perfect has mostly taken over the functions of the perfective, and the subjunctive and periphrastic prospective have mostly replaced the prospective.
Declines using third-person suffix pronouns instead of adjectival endings: masculine .f/.fj, feminine .s/.sj, dual .sn/.snj, plural .sn.
^ Gundacker, Roman (2011) “On the Etymology of the Egyptian Crown Name mrsw.t*: An “Irregular” Subgroup of m-Prefix Formations” in Lingua Aegyptia, volume 19, page 46