Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “sit up”

See all translations

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?
Add Cambridge dictionaries to your browser to your website

Definitions of “sit up” in other dictionaries

Word of the Day

christmassy

typical of Christmas, or happy because it is Christmas

Word of the Day

Cleavage proves divisive in Cambridge’s words of 2014

by Alastair Horne,
December 19, 2014
​​​​ Other dictionaries may choose faddish novelties as their words of the year, but here at Cambridge, we like to do something different. We look for the words that have seen sudden surges in searches over the course of the year – words that have been baffling users of English and driven them

Read More 

tweleb noun

December 22, 2014
informal a Twitter celebrity; (more specifically, someone who has more than 1,000 followers on Twitter) There were a few old and a few new faces, including a tweleb or two. Expect to see and hear more from these cool kids.

Read More