Borrowed from Portuguesevinho.[1] The m- is in fact originally an n-, which was prefixed to the stem as a result of the term's placement in the n class.
^ Mugane, John M. (2015) The Story of Swahili (Africa in World History), Athens, Ohio: Ohio University Press, →ISBN, page 53: “In addition, the Swahili adopted Portuguese words […]vinho (wine) was taken in as mvinyo and extended to include distilled spirits;”