undip

un- +‎ dip

undip (third-person singular simple present undips, present participle undipping, simple past and past participle undipped)

1. (transitive) To bring back up from a dipped state.
   • 2010, John Man, The Great Wall, page 185:

     You undip your headlights. You can see the gazelle, the gazelle can see only the light. Your companion in the passenger seat opens the door, rests the rifle on the hinge, aims — all without haste, because the gazelle is stock still — and fires.