IPA: /ˈθɜːroʊˌɡoʊɪŋli/
KK: /ˈθɜroʊˌɡoʊɪŋli/
In a way that is complete and thorough, leaving no part out.
She examined the report thoroughlygoingly to ensure all details were correct.
Thoroughgoingly → It is formed from "thorough" (from Old English *þurh*, meaning through) and "going" (from Old English *gān*, meaning to go) combined with the adverbial suffix "-ly" (meaning in a manner of). The word "thoroughgoingly" means in a manner that goes through completely or thoroughly.
Think of going 'through' ('thorough') something completely, and the '-ly' means in that manner. This helps you remember that 'thoroughgoingly' means doing something in a complete and thorough way.