end has 16 distinct synonyms spread across 10 of its 18 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 3 recorded opposites are beginning, middle, begin.
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 point in time at which something ends
“the end of the year”
the final stage or concluding parts of an event or occurrence
“the end was exciting”
the surface at either extremity of a three-dimensional object
“one end of the box was marked `This side up'”
a boundary marking the extremities of something
“the end of town”
one of two places from which people are communicating to each other
“the phone rang at the other end”
the part you are expected to play
“he held up his end”
the last section of a communication
“in conclusion I want to say...”
a piece of cloth that is left over after the rest has been used or sold
(American football) a position on the line of scrimmage
“no one wanted to play end”
put an end to
“The terrible news ended our hopes that he had survived”
Synonyms, antonyms and the broader and narrower relations for end come from Princeton University’s WordNet. Full sources and licences.