bed has 26 distinct synonyms spread across 5 of its 13 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 piece of furniture that provides a place to sleep
“he sat on the edge of the bed”
a plot of ground in which plants are growing
“the gardener planted a bed of roses”
a depression forming the ground under a body of water
“he searched for treasure on the ocean bed”
the flat surface of a printing press on which the type form is laid in the last stage of producing a newspaper or magazine or book etc.
a foundation of earth or rock supporting a road or railroad track
“the track bed had washed away”
place (plants) in a prepared bed of soil
Synonyms, antonyms and the broader and narrower relations for bed come from Princeton University’s WordNet. Full sources and licences.
put to bed
“The children were bedded at ten o'clock”
have sexual intercourse with
“This student sleeps with everyone in her dorm”