C13: from Old French mercier dealer, from Vulgar Latin merciārius (unattested), from Latin merx goods, wares
Mercer in British English
(ˈmɜːsə)
noun
Johnny, full name John Herndon Mercer. 1909–76, US popular songwriter and singer. His most popular songs include "Blues in the Night" (1941) and "Moon River" (1961)
mercer in American English
(ˈmɜrsər)
noun
British
a dealer in textiles; dry goods merchant
Word origin
OFr mercier < merz, goods < L merx, wares: see market