IPA: /ˌɪntəˈkɒləniəl/
KK: /ˌɪntərˈkoʊləniəl/
Relating to or occurring between different colonies.
The intercolonial trade agreements helped boost the economies of the regions involved.
Intercolonial → It is formed from "inter-" (meaning between) and "colonial" (from Latin "colonia", meaning a settlement or colony). The word "intercolonial" refers to something that exists or occurs between different colonies.
Think of things that happen 'between' ('inter-') different 'settlements' ('colonial') — that's what intercolonial means.
No commonly confused words.