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.

1) Recognition of the existence or truth of something.
2) An expression of appreciation (Dictionary.com).

→ acknowledge; → -ment.

1) To perceive or understand as fact or truth; to apprehend clearly and with certainty.
2) To have established or fixed in the mind or memory (Dictionary.com).

M.E. knowen, knawen, from O.E. cnâwan, akin to O.H.G. bichnâan "to recognize," L. gnoscere, noscere "to come to know," Gk. gignoskein, Pers. šenâxtan, dânestan, as below.

Dânestan "to know;" Mid.Pers. dânistan "to know;" variant šenâxtan, šenâs- "to recognize, to know" (Mid.Pers. šnâxtan, šnâs- "to know, recognize"); O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge," cognate with L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); P.Gmc. *knoeanan; O.E. cnawan, E. know, as above; Rus. znat "to know;" PIE base *gno- "to know."

1) Acquaintance with facts, truths, or principles, as from study or investigation.
2) All the information, facts, truths, and principles learned throughout time.

M.E. cnawlece, from O.E. cnawan, cf. O.H.G. bi-chnaan, ir-chnaan "to know;" cognate with Pers. šenâxt, as below.

1) Šenâxt, past stem of šenâxtan, šenâsidan "to know, discern, distinguish, be acquainted with;" Mid.Pers. šnâxtan, šnâs- "to know, recognize," dânestan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know."
2) Dânestgân, literally "body of (what is) known," from dânest, short for dâneste "known," p.p. of dânestan variant of šenâxtan, as above, + -gân suffix forming plural entities.

Math.: A → variable or → function whose → value is to be found.

→ un-, + known, p.p. of → know.