Other forms: assured, assures, assuring
To assure somebody is to tell them firmly that they need not worry. I assure you, she assured him it was fine, rest assured.
It takes a person as its object, which is the key to the trio that confuses everybody. Assure a person that something is true. Ensure that something happens. Insure a thing against loss. Three words, three jobs, and mixing them up is one of the commonest errors in business writing. Note rest assured, a fixed and slightly formal phrase, and that in Britain life assurance is the insurance term for a policy that pays on a certain event.
1verbassureTo tell somebody firmly that something is true so they stop worrying.
“He assured her that nothing had been lost.”
synonyms: reassure, promise
2verbcertainTo make something certain.
“Two goals in five minutes assured the win.”
Too few real examples of this word to estimate which sense is commonest.
assure is a way of reassuring.
Also accepted in games: reassure
Old French asseurer comes from Latin securus, free from care — the same root as secure and sure. To assure somebody is to make them secure in their mind, and insure and ensure are the same word arriving with different spellings and different jobs.
Latin
ad-
Old French
asseurer
English, today
assure
Built from
From Old French asseurer (Modern French assurer), from Latin ad- + securus (“secure”). Cognate with Spanish asegurar. a doublet of assecure.
Etymology from Wiktionary, CC BY-SA