Kiwi asks…
Do "blue" and "yellow" have a plural form?
Answer from a Native speaker

Rebecca
The nouns blue and yellow are both countable and uncountable. If you are talking about a single shade of blue of yellow, the plural form is still blue or yellow. However, if you're talking about different shades (for example dark blue, sky blue, navy, cobalt) then the plural becomes blues or yellows.
Listening Quiz
1/2 STEP LEARN