in Latin, the form of com- "together, with" in compounds with stems beginning in vowels, h-, and gn-; see com-. Taken in English from 17c. as a living prefix meaning "together, mutually, in common".
In Latin, "to get to know, recognize," from assimilated form of com "together" (see co-) + gnoscere "to know" (from PIE root *gno- "to know").
In Latin, past participle stem of cognoscere "to get to know, recognize," from assimilated form of com "together" (see co-) + gnoscere "to know" (from PIE root *gno- "to know").
"to know" (from Proto-Indo-European root *gno- "to know").