oil yellow

noun

1

often capitalized O&Y

a

: any of several oil-soluble yellow dyes

b

or oil yellow II : a carcinogenic azo dye C₆H₅N₂C₆H₄N(CH₃)₂ formerly used in coloring butter and oils; para-dimethyl-aminoazobenzene

called also butter yellow, methyl yellow

2

: a moderate greenish yellow that is greener and duller than citron yellow and deeper than linden green

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