adieu / ado 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. 👇
adieu: (noun) a farewell remark.
ado: NA
adieu: ah·d·UW
ado: ah·d·UW
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)