Word Origin & History
from L., archaic form of classical L. cum "together, together with, in combination," the prefix sometimes used as an intensive, from PIE *kom- "beside, near, by, with" (cf. O.E. ge-, Ger. ge-). Before vowels and aspirates, reduced to co-; before -g-, assimilated to cog- or con-; before -l-, assimilated
to col-; before -r-, assimilated to cor-; before -c-, -d-, -j-, -n-, -q-, -s-, -t-, -v- assimilated to con-.