koloro

The construction to memorise is de: the colour of something is la koloro de la maro, and a thing of a given colour is vesto de hela koloro. Both take de where English shuffles between of and a bare adjective.

Derivations run smoothly. Kolora is coloured, kolorigi is to colour something in, senkolora is colourless, and multkolora is multicoloured. Green is not a random pick in the third example either: verda is the movement's own colour, and la verda stelo is its emblem.