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1. To literally brighten or illuminate something. In this usage, "light up" is usually a set phrase. Fireworks lit up the night sky.
2. To become illuminated. In this usage, "light up" is usually a set phrase. The street lamps light up at dusk.
3. To focus a light source on someone or something. In this usage, "light up" is usually a set phrase. The flashlight lit up a stray cat in the bushes.
4. To become noticeably excited or animated at the sight of someone or something. In this usage, "light up" is usually a set phrase. I'm sure she likes you—she just lights up whenever you're around.
5. To cause someone to become noticeably excited or animated. I'm sure she likes you—you just light her up whenever you're around.
6. To light something that can be smoked, such as a cigarette. Please don't light up in my new car—I don't want it to smell like smoke.
7. To ignite something. I used a match to light up the pilot on the stove.
8. To become ignited or begin to burn. In this usage, "light up" is usually a set phrase. The firewood still hasn't lit up—what am I doing wrong?
light someone or something up
to shine lights on someone or something. (See also light something up.) We lit Fred up with the headlights of the car. Light up the stage and let's rehearse.
light something up
1. to light a fire, a gas burner, etc. I lit the kindling up and soon the fire was going. You light up the stove and get dinner going.
2. to light something to smoke, such as a cigarette, pipe, etc. (See also light someone or something up.) She lit the cigarette up and took in a great breath of the smoke. She lit up a cigarette.
1. to become brighter. Suddenly, the sky lit up like day. The room lit up as the fire suddenly came back to life.
2. [for someone] to become interested and responsive in something. We could tell from the way Sally lit up that she recognized the man in the picture. She lit up when we told her about our team's success.
1. Become or cause to become more animated or cheerful, as in Her laughter lit up the whole room, or His face lit up when he saw her. This expression transfers physical illumination to human moods. Also see lighten up. [Mid-1700s]
2. Start smoking a cigar, cigarette, or pipe, as in The minute he got outside the church he lit up. [Colloquial; mid-1800s]
1. To illuminate or be illuminated: All the neon signs along the street light up at night.
2. To cause something to illuminate or be illuminated: The morning sun lit up the room. The miners lit their headlamps up and descended into the shaft.
3. To begin to burn: The gas burners lit up on the first try.
4. To cause something to burn; ignite something: I lit up a match and started the fire. I'll get some wood and light a fire up.
5. To ignite and begin smoking something, especially a cigarette, cigar, or pipe: I went out to the porch and lit up a cigar. He lit his pipe up with a match. She took a cigarette from the case and lit up.
6. To become animated or cheerful: The children's eyes lit up when they saw the size of the cake.
7. To cause someone or something to become animated or cheerful: The presence of the movie star lit up the room. He was feeling sad, but the surprise party lit his face up.