word-forming element usually meaning "with, together," from Latin com, archaic form of classical Latin cum "together, together with, in combination," from PIE *kom- "beside, near, by, with" (compare Old English ge-, German ge-). The prefix in Latin sometimes was used as an intensive.
Before vowels and aspirates, it is reduced to co-; before -g-, it is assimilated to cog- or con-; before -l-, assimilated to col-; before -r-, assimilated to cor-; before -c-, -d-, -j-, -n-, -q-, -s-, -t-, and -v-, it is assimilated to con-, which was so frequent that it often was used as the normal form.
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.