verb/ʁe.vɛ.jɔ.ne/
to celebrate Christmas Eve or New Year's Eve, especially by having dinner with friends and/or family
“On va aller réveillonner chez des copains.” — We're going to have dinner at some friends' place on Christmas Eve [or on New Year's Eve].
From réveillon (“meal on Christmas Eve or New Year's Eve”) + -er.