colonise has 1 distinct synonym spread across 2 of its 2 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is decolonise.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
settle as a colony; of countries in the developing world
“Europeans colonized Africa in the 17th century”
Synonyms, antonyms and the broader and narrower relations for colonise come from Princeton University’s WordNet. Full sources and licences.