IPA: /ˈmʌltiˌɡruːp/
KK: /mʌltiˌɡruːp/
Relating to or involving multiple groups.
The multigroup study included participants from various backgrounds.
Multigroup → It is formed from "multi-" (meaning many) and "group" (from Old French *groupe*, meaning a collection or assembly). The word "multigroup" refers to a collection or assembly of many groups.
Think of 'many' ('multi-') coming together in a 'collection' ('group') — that's what multigroup means.
No commonly confused words.