continuation has 7 distinct synonyms spread across 4 of its 4 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 discontinuation.
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.
the act of continuing an activity without interruption
a Gestalt principle of organization holding that there is an innate tendency to perceive a line as continuing its established direction
the consequence of being lengthened in duration
Synonyms, antonyms and the broader and narrower relations for continuation come from Princeton University’s WordNet. Full sources and licences.