acknowledge Look up acknowledge at Dictionary.com
1550s, a blend of M.E. aknow (from O.E. oncnawan "understand," from on + cnawan "recognize;" see know) and M.E. verb knowlechen "admit." Somehow, in the merger, a parasitic -c- slipped in, so that, while the kn- became a simple "n" sound (as in know), the -c- stepped up to preserve, in this word, the ancient "kn-" sound.