COO

UK: 'COO': /ˌsiːəʊˈəʊ/; 'coo': /ˈkuː/

US: /ku/

US: 'coo': (ko̅o̅); 'Coo': (kô′ô)

Inflections of 'coo' (v): (⇒ conjugate)

coos

v 3rd person singular

cooing

v pres p

cooed

v past

cooed

v past p

Collins Concise English Dictionary © HarperCollins Publishers::

COO abbreviation

1. chief operating officer

WordReference Random House Learner's Dictionary of American English © 2026

coo¹ /ku/   v., cooed, coo•ing, n. 
v. 

1. to make or imitate the soft, murmuring sound of doves: [no object]
   the baby cooing quietly in the bassinet.
   [~ + object]
   cooing a quiet tune.

n. [countable]

2. a cooing sound.

WordReference Random House Unabridged Dictionary of American English © 2026

coo¹  (ko̅o̅), v., cooed, coo•ing, n. 
v.i. 

1. to utter or imitate the soft, murmuring sound characteristic of doves.
2. to murmur or talk fondly or amorously.

v.t. 

3. to utter by cooing.

n. 

4. a cooing sound.

• imitative 1660–70

coo′er, n. 
coo′ing•ly, adv. 

coo²  (ko̅o̅), interj. [Brit. Slang.]

1. British Terms (used to express surprise or amazement.)

• origin, originally uncertain 1910–15

Co•o  (kô′ô), n. 

1. Place Names Italian name of Kos. 

COO, 

1. chief operating officer.

Collins Concise English Dictionary © HarperCollins Publishers::

coo / kuː/ verb (coos, cooing, cooed)

1. (intransitive) (of doves, pigeons, etc) to make a characteristic soft throaty call
2. (transitive) to speak in a soft murmur
3. (intransitive) to murmur lovingly (esp in the phrase bill and coo)

noun

1. the sound of cooing

interjection

1. an exclamation of surprise, awe, etc