An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) To admit to be real or true; recognize the existence, truth, or fact of.
2) To recognize the authority, validity, or claims of.
3) To show or express appreciation or gratitude for (Dictionary.com).

A blend of M.E aknow "admit or show one's knowledge" (from O.E. oncnawan "understand") and M.E. knowlechen "to admit."

Âdânidan, from âdân, from prefix â- + dân present stem of dânestan, → know; cf. Sogd. âzân, azân "to acknowledge, to confess," from prefixed zân, variant of dân.