noun
Usage: often capitalized A&Y
: any of various mordant dyes not related chemically to alizarin but applicable by similar methods: as
a. : a monoazo dye made by coupling diazotized m- nitroaniline with salicylic acid — called also Alizarine Yellow 2G ; see dye table I (under Mordant Yellow 1 )
b. : a monoazo dye made by coupling p- nitroaniline with salicylic acid and used chiefly as an acid-base indicator — called also Alizarine Yellow R ; see dye table I (under Mordant Orange 1 )
c. : gallacetophenone — called also Alizarine Yellow C