mongrel (n.)

"in, in the midst of," early 12c., from Old English onmang, in late Old English sometimes amang, a contraction of ongemang "among, during," from phrase on gemang, literally "in the crowd or company (of)," from on (see a- (1)) + gemengan "to mingle," from Proto-Germanic *mangjan "to knead together," which is perhaps from a nasalized form of PIE root *mag- "to knead, fashion, fit." The collective prefix ge- was dropped 12c. leaving onmong, amang, among. Compare Old Saxon angimang "among, amid;" Old Frisian mong "among."

mid-15c., menglen, transitive, "mix, blend, form a combination of, bring (something and something else) together," frequentative of Middle English myngen "to mix," from Old English mengan (related to second element in among), from Proto-Germanic *mangjan "to knead together" (source also of Old Saxon mengian, Old Norse menga, Old Frisian mendza, German mengen), from a nasalized form of PIE root *mag- "to knead, fashion, fit."

The formation may have been suggested by cognate Middle Dutch mengelen. Intransitive sense of "to be or become joined, combined, or mixed" is by 1520s. Of persons, "enter into intimate relation, join with others, be sociable," from c. 1600. Related: Mingled; mingling; minglement.