thoroughinvestigation
nounUK /ˈθʌrə ɪnˌvɛstɪˈɡeɪʃən/
US /ˈθɜːroʊ ɪnˌvɛstɪˈɡeɪʃən/
A careful search to find out all the facts about something.
The police did a thorough investigation to find the missing bike.
OTHER MEANINGS
2. A complete check to make sure everything is correct and safe.
The school did a thorough investigation of the playground before letting kids play.
3. A long, careful look into a problem to understand what caused it.
Her thorough investigation of the broken toy showed the battery was dead.
4. A careful study of a subject to learn everything about it.
His thorough investigation of dinosaurs helped him win the science quiz.