coo / coup are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
coo: (noun) the sound made by a pigeon. (verb) speak softly or lovingly. (verb) cry softly, as of pigeons.
coup: (noun) a brilliant and notable success.
coo: k·UW
coup: k·UW
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)