grey has 17 distinct synonyms spread across 13 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.
Queen of England for nine days in 1553; she was quickly replaced by Mary Tudor and beheaded for treason (1537-1554)
Englishman who as Prime Minister implemented social reforms including the abolition of slavery throughout the British Empire (1764-1845)
any organization or party whose uniforms or badges are grey
“the Confederate army was a vast grey”
a neutral achromatic color midway between white and black
showing characteristics of age, especially having grey or white hair
“whose beard with age is hoar”
Synonyms, antonyms and the broader and narrower relations for grey come from Princeton University’s WordNet. Full sources and licences.
used to signify the Confederate forces in the American Civil War (who wore grey uniforms)
“a stalwart grey figure”
intermediate in character or position
“a grey area between clearly legal and strictly illegal”