If you’ve never studied a language that has gender and number as modification of adjectives you may find menus (and especially just extracting words from menus to create a glossary) confusing. Usually the adjective (color, in this post) precedes a noun and that noun may be singular or plural (cebolla, cebollas; mejillón, mejillónes – easy as similar to English, in general) and most nouns have gender cebolla (feminine) and cordero (masculine) [ending in o (masc) or a (fem) is usually a good clue]. So a word for color itself has to change based on number or gender.
Also note, unlike English, that typically in Spanish the noun comes before the modifying adjective,
For instance, negro (black) is negro, negra, negros, negras depending on gender and number of the noun it modifies, as in frijoles negros or aceituna negra.
So here are most of the colors you’d find on menus:
|masc sing.||fem sing.||masc plural||fem plural|
violeta does not depend on either gender or number; azul, verde, gris don’t depend on gender.
A couple of other colors I’ve fished out of menus are shown below but I haven’t found their gender/number variations, so take your best guess.
btw: I find it amusing that one Spanish word I should know is Amarillo (yellow) since I was born in a town of that name in Texas. Of course we pronounced it wrong actually saying the ll (versus y sound in Spanish). I wonder what a Spaniard might think if I said I was born in that town and used our corrupted pronunciation.