Mercer

google

ref

Middle English: from Old French mercier, based on Latin merx, merc- ‘goods’.

wiktionary

ref

From Anglo-Norman marcer, mercer(“merchant, textile merchant”), from merz(“commodity”) (from Latin merx).

etymonline

ref

mercer (n.)

"dealer in small wares or merchandise of any sort," also, specifically, "dealer in textiles or clothes of any sort, especially silk," c. 1200 (late 12c. as a surname), from Old French mercier "shopkeeper, tradesman," from Vulgar Latin *merciarius, from Latin merx "wares, merchandise" (see market (n.)). Related: Mercery.