yard has 15 distinct synonyms spread across 5 of its 9 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 unit of length equal to 3 feet; defined as 91.44 centimeters; originally taken to be the average length of a stride
the enclosed land around a house or other building
“it was a small house with almost no yard”
a tract of land enclosed for particular activities (sometimes paved and usually associated with buildings)
“they opened a repair yard on the edge of town”
the cardinal number that is the product of 10 and 100
a tract of land where logs are accumulated
an area having a network of railway tracks and sidings for storage and maintenance of cars and engines
an enclosure for animals (as chicken or livestock)
Synonyms, antonyms and the broader and narrower relations for yard come from Princeton University’s WordNet. Full sources and licences.