the common European blackbird, late 15c., from Old French merle (12c.), from Latin merulus, from PIE *ams- "black, blackbird" (source also of Old English osle "blackbird;" see ouzel). Middle English had the word earlier as merule (late 14c.), directly from Latin. "Perhaps never in popular use, but constantly occurring in Scottish poetry from the 15th c." [OED]. The Latin word shows effects of rhotacism. It also is the source of Provençal and Spanish merla, Portuguese melro, and Italian merla. Borrowed from French are Middle Dutch and dialectal German merle, Dutch meerle.