light up

light up (third-person singular simple present lights up, present participle lighting up, simple past and past participle lit up)

1. (transitive) To illuminate, to bring light to something, to brighten.
   • 1922 February, James Joyce, Ulysses, Paris: Shakespeare & Co.; Sylvia Beach, OCLC 560090630; republished London: Published for the Egoist Press, London by John Rodker, Paris, October 1922, OCLC 2297483:

     Episode 12, The Cyclops:

     The deafening claps of thunder and the dazzling flashes of lightning which lit up the ghastly scene testified that the artillery of heaven had lent its supernatural pomp to the already gruesome spectacle.

   • 2009, President Nixon's Pilot, Jim Bell, in The Propinquity Effect →ISBN:

     When we cranked up the engine, the fire warning light lit up.

2. (transitive) To show an increase in activity or a brightening of mood.
   • 1956 [1880], Johanna Spyri, Heidi, translation of original by Eileen Hall, page 84:

     Clara's eyes lit up at this highly unusual occurrence.

   He saw Mary and his face lit up.

3. (intransitive) To light a cigarette, pipe, etc.

   Smoking in this building is not allowed, so I always step outside to light up.

4. (transitive) To make happy.
   • 2001, Ash, Shining Light

     You are a shining light, and you light up my life.

   • 2010, WLTX.com, Young Girl Continues Bike Giveaway Tradition, 25 Nov 2010

     "It lights me up, make me happy. Sometimes I go home, go in my room and cry with joy,"said Hudson smiling

5. (transitive, slang) To open fire on a target or group of targets.
6. (chiefly US, transitive, slang) To shock (someone) with a stun gun.

• uplight