Question

If an orange is orange, why isn’t a lime called a green or a lemon called a yellow?

Answer 1

beacuse by default we have two meanings of orange... one is describing a colour, and another, a fruit...thats why people prefer calling an orange as orange.
Whereas a lime is a fruit whose colour is defined by default in english i. e. it is green in colour and same goes for lemon being yellow.

hope it helped you

Answer 2

because orange is a name of colour.

lime,lemon etc.are not the names of colours