Mam
来自Big Physics
mid 16th century (in mam (sense 1)): perhaps imitative of a child's first syllables (see mama); mam (sense 2) is a variant of ma'am.
wiktionary
Alteration or clipping of mama. Compare Scots mam, Old Scots mame(“mother”), mamye(“wet nurse”), Saterland Frisian Määme(“mother”), West Frisian mem(“mother”). Alternatively, possibly either conserved from or influenced by earlier Brythonic language.
