light up
B2Informal to neutral
Definition
Meaning
To illuminate or make brighter with light; to begin to shine.
To become happy, animated, or excited; to cause something to become more lively or interesting; to ignite a cigarette or other substance.
Linguistics
Semantic Notes
Most commonly functions as a phrasal verb. The primary meanings can be grouped into: 1) literal illumination (transitive/intransitive), 2) figurative for facial expression/animation (intransitive), 3) slang for smoking (transitive). The figurative use often implies a sudden, positive change.
Dialectal Variation
British vs American Usage
Differences
No significant difference in core meaning. The slang use for smoking a cigarette or a joint is common in both. Minor spelling differences may apply in derivatives (e.g., 'lighted up' vs. 'lit up', though 'lit up' is more common for both in past tense).
Connotations
Similar connotations in both varieties. The figurative use ('her face lit up') is universally positive.
Frequency
Equally frequent and idiomatic in both varieties.
Vocabulary
Collocations
Grammar
Valency Patterns
[NP] lights up (intransitive)[NP] lights up [NP] (transitive)[NP] lights up with [Emotion/NP] (intransitive + prepositional phrase)Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “Light up like a Christmas tree (to become very brightly lit or very happy/animated)”
Usage
Context Usage
Business
Rare. Possibly used in marketing/design contexts ('The new display really lights up the store').
Academic
Rare, except in literary analysis to describe a character's reaction.
Everyday
Very common in both literal ('I'll light up the barbecue') and figurative ('His face lit up when he saw her') contexts.
Technical
Used in electronics/lighting ('The LED array lights up sequentially').
Examples
By Part of Speech
verb
British English
- The sensors light up when movement is detected.
- He lit up a fag outside the pub.
- Her whole face lit up with delight.
American English
- The sky lights up during the fireworks show.
- She lit up a cigarette on the porch.
- His eyes lit up when he saw the present.
adverb
British English
- Not typically used as a standalone adverb.
American English
- Not typically used as a standalone adverb.
adjective
British English
- The newly lit-up square looked magical.
- A light-up keyboard is useful in the dark.
American English
- The lit-up skyline was breathtaking.
- She bought light-up sneakers for her kid.
Examples
By CEFR Level
- Please light up the room, it's dark.
- The Christmas tree lights up at night.
- Her smile lit up the whole room.
- He stopped to light up a cigarette.
- The data on the screen lit up, indicating a problem.
- The city lights up beautifully during the festival.
- The discovery lit up the scientific community, sparking intense debate.
- His narrative has moments that light up with incisive wit.
Learning
Memory Aids
Mnemonic
Think of a light bulb switching on over someone's head when they have an idea – their face LIGHTS UP.
Conceptual Metaphor
HAPPINESS IS LIGHT; EXCITEMENT/INTEREST IS IGNITION.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct calque 'светить вверх'. Use 'загораться' (for faces/screens), 'освещать' (for rooms), or 'прикуривать' (for cigarettes).
- The phrase is not directional ('up') but completive/intensifying.
Common Mistakes
- Using 'light up' to mean 'to lift a light' (incorrect).
- Confusing with 'lighten up' (which means 'to become less serious').
- Incorrect past tense: 'lighted up' is possible but less common than 'lit up'.
Practice
Quiz
In which context is 'light up' LEAST appropriate?
FAQ
Frequently Asked Questions
Both 'lit up' and 'lighted up' are correct, but 'lit up' is far more common in everyday speech and writing for both literal and figurative uses.
Yes. It can be used for any source of illumination (screens, signs, rooms, skies) and figuratively for anything becoming lively or animated (e.g., 'The conversation lit up when politics was mentioned').
'Light up' primarily means to illuminate or become animated. 'Lighten up' is an idiomatic phrasal verb meaning 'to become more relaxed or less serious'.
Yes, it's a separable phrasal verb. You can say 'He lit the room up' or 'He lit up the room'. However, when the object is a pronoun, it must separate: 'He lit it up' (not 'He lit up it').