Other forms: realized, realizes, realizing
To realise something is to suddenly understand what you had not understood before. I realised I had left the keys inside. She realised he was serious.
It is a state verb and so it is not usually continuous: I realise, not I am realising. It takes a that-clause, and the that is optional in speech. The second sense is formal and quite different: to realise a plan or an ambition is to make it real, to bring it about — a dream realised, realise your potential. Finance has a third: to realise an asset is to sell it and turn it into money. Note the spelling — realise in British English, realize in American, and Oxford style prefers -ize even in Britain.
1verbrealizeTo become aware of something you had not noticed.~23%
“I did not realise how late it was.”
synonyms: understand, grasp, appreciate
2verbplanTo make a plan or an ambition happen.~69%
“It took twenty years to realise the project.”
3verbsellTo sell something and turn it into money.~8%
“The estate realised rather less than expected.”
Shares are an estimate: a language model read 14 sentences found in the wild and placed 13 of them on a sense (1 were unclear) — a count of our sample, not a measurement of English.
realize is a way of coming to understand.
Also accepted in games: realise
French realiser meant to make real, from Latin realis, from res, a thing. The sudden-understanding sense is English's own invention and about two hundred years old: it is the moment a thing becomes real to you rather than in the world.
Proto-Indo-European
*reh₁ís — goods; wealth
Latin
reālis — actual, real
Old French
reel
Middle French
réaliser — to make real; to convert (something) into assets or cash
French
réaliser
English, today
realize
Built from
From real + -ize. From real + -ize, possibly modelled after French réaliser, Middle French réaliser (“to make real; to convert (something) into assets or cash”), from real (“actual, real”) + -iser. Real is derived from Old French reel, from Latin reālis (“actual, real”), from rēs (“deed; event; matter; thing”) (ultimately from Proto-Indo-European reh₁ís (“goods; wealth”)) + -ālis.
Etymology from Wiktionary, CC BY-SA