Late 16th century; earliest use found in Lodowick Lloyd (fl. 1573–1607). From classical Latin medimnus (masculine; also medimnum, neuter) from ancient Greek μέδιμνος, denoting both a dry measure and a land measure. The μεδ- in μέδιμνος is probably cognate with mete; the -μνος termination may be compared with -mnus in classical Latin alumnus; the -ι- remains unexplained.