Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “sit up”

sit up

verb uk phrasal verb with sit   /sɪt/ (present participle sitting, past tense and past participle sat) us  

(STRAIGHT)

to sit with a straight back: How many times do I have to tell you children to sit up straight?

(STAY AWAKE)

to stay awake and not go to bed although it is late: [+ -ing verb] The book was so interesting that I sat up all night reading it. I'll be late tonight, so don't sit up for (= wait for) me.

(NOTICE)

informal to show interest or surprise: The news that he was getting married really made her sit up.
(Definition of sit up phrasal verb, verb from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of sit up?
Browse related topics

You are looking at an entry to do with Paying attention and being careful, but you might be interested in these topics from the Attention and care topic area:

Add Cambridge dictionaries to your browser to your website

Definitions of “sit up” in other dictionaries

Word of the Day

look on the bright side

to find good things in a bad situation

Word of the Day

The language of work

by Kate Woodford,
October 15, 2014
Most of us talk about our jobs. We tell our family and friends interesting or funny things that have happened in the workplace (=room where we do our job), we describe – and sometimes complain about – our bosses and colleagues and when we meet someone for the first time, we tell

Read More 

life tracking noun

October 20, 2014
the use of one or more devices or apps to monitor health, exercise, how time is spent, etc.

Read More