Recorded since 1553, a blend of Middle English aknowen and knowlechen ("to discover, reveal, acknowledge"). The former verb is from Old English oncnāwan, from on + cnāwan ("to know").

The /k/-sound was preserved by being redistributed to the preceding syllable: /əˈkn-/ > /əkˈn-/. The -c- was inserted accordingly to reflect this pronunciation more clearly.

• (RP) IPA: /əkˈnɒl.ɪd͡ʒ/, [əkˈnɒlɨ̞d͡ʒ], [əɡˈnɒlɨ̞d͡ʒ]
• (America) IPA: /əkˈnɑl.ɪd͡ʒ/, [əkˈnɑːɫəd͡ʒ], [ɨkˈnɑːɫɨd͡ʒ], [əɡˈnɑːɫəd͡ʒ], [ɨɡˈnɑːɫɨd͡ʒ]

acknowledge (acknowledges, present participle acknowledging; simple past and past participle acknowledged)

1. (transitive) To admit the knowledge of; to recognize as a fact or truth; to declare one's belief in

   to acknowledge the being of a god

   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Psalm 51:3 ↗:

     I acknowledge my transgressions.

   • 1631 (first performance), Philip Massinger, The Emperour of the East. A Tragæ-comœdie. […], London: […] Thomas Harper, for Iohn Waterson, published 1632, →OCLC ↗, Act IV, scene iii ↗:

     [T]he charge of my moſt curious, and coſtly ingredients fraide, amounting to ſome ſeaventeene thouſand crovvnes, a trifle in reſpect of health, vvriting your noble name in my Catalogue, I ſhall acknovvledge my ſelfe amply ſatisfi'd.

   • 1849–1861, Thomas Babington Macaulay, chapter 1, in The History of England from the Accession of James the Second, volume (please specify |volume=I to V), London: Longman, Brown, Green, and Longmans, →OCLC ↗:

     For ends generally acknowledged to be good.

2. (transitive) To own or recognize in a particular quality, character or relationship; to admit the claims or authority of; to give recognition to.
   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Proverbs 3:6 ↗:

     In all thy ways acknowledge Him.

   • c. 1591–1595 (date written), William Shakespeare, “The Tragedie of Romeo and Ivliet”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act III, scene v]:

     By my soul, I'll ne'er acknowledge thee.

3. (transitive) To be grateful of (e.g. a benefit or a favour)

   to acknowledge a favor

   • 1667, John Milton, “Book XI”, in Paradise Lost. […], London: […] [Samuel Simmons], and are to be sold by Peter Parker […]; [a]nd by Robert Boulter […]; [a]nd Matthias Walker, […], →OCLC ↗; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873, →OCLC ↗:

     They his gifts acknowledged none.

4. (transitive) To report (the receipt of a message to its sender).

   This is to acknowledge your kind invitation to participate in the upcoming debate.

5. (transitive) To own as genuine or valid; to assent to (a legal instrument) to give it validity; to avow or admit in legal form.

• (admit knowledge of) avow, recognize, admit
• (recognize a quality) recognize, admit, allow, concede, confess, own
• (be grateful of)
• (report receipt of message)

• acknowledgment

• French: reconnaître
• German: zur Kenntnis nehmen, erkennen, bekennen
• Italian: riconoscere, ammettere
• Portuguese: reconhecer
• Russian: признава́ть
• Spanish: reconocer

• German: anerkennen
• Italian: riconoscere
• Portuguese: reconhecer, admitir
• Spanish: reconocer

• Portuguese: reconhecer

• French: accuser réception
• German: den Empfang bestätigen
• Italian: confermare
• Portuguese: confirmar
• Russian: подтвержда́ть
• Spanish: acusar recibo

• French: certifier
• Portuguese: reconhecer