A word appearing as G. mang “butter” in the Gnomish Lexicon of the 1910s (GL/28), clearly related to ᴱQ. manya “butter” and thus derived from the early root ᴱ√MṆGṆ (QL/62).

Neo-Sindarin: I’d retain ᴺS. mang “butter” for purposes of Neo-Sindarin from a Neo-Root ᴺ√MANGYA, where ngy became ng in (Old) Sindarin (PE19/23).