This is the 10073rd most frequent French word.
grimer
To make up or disguise (using makeup).
'Grimer' is used here to describe the act of applying makeup or paint to one's face as part of a costume.
Je vais grimer mon visage pour la fête costumée.
I will paint my face for the costume party.
'Grimer' is used here to describe the transformation of someone into a character using makeup or costumes.
Il a été grimé en clown pour amuser les enfants.
He was made up as a clown to entertain the children.
'Grimer' is used to describe actors using makeup to prepare for a performance.