dipper has 10 distinct synonyms spread across 4 of its 5 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
a ladle that has a cup with a long handle
a cluster of seven stars in Ursa Minor; at the end of the dipper's handle is Polaris
a group of seven bright stars in the constellation Ursa Major
small North American diving duck; males have bushy head plumage
small stocky diving bird without webbed feet; frequents fast-flowing streams and feeds along the bottom
Synonyms, antonyms and the broader and narrower relations for dipper come from Princeton University’s WordNet. Full sources and licences.