An Etymological Dictionary of the German Language/Mohn
Mohn, m., from the equiv. late MidHG. mân, earlier mâhen, m., ‘poppy’; OHG. *mâhan is wanting, for which OHG. mâgo, MidHG. mâge, m., ‘poppy,’ with a change of h to g (see fragen and Zähre), is used (comp. Goth. þahan with OHG. dagên, Lat. tacere); to this UpG. mâgsame (Alsat. mâss), ‘poppy,’ is allied. It corresponds to OSwed. valmughi, Swed. vallmo, ‘poppy.’ The word points to pre-Teut. mêkon-, besides which the form mâkon- is presupposed by Gr. μήκων (Dor. μᾶκων), OSlov. makŭ, ‘poppy.’ These correspondences, however, do not necessarily imply that the cognates are of genuine Aryan origin (comp. Hanf). For OHG. mâgo a form popig (E. poppy) was used in AS., based on Lat. papaver.