ensure
Formsensures, ensuring, ensured
Often confused with insure
- 1To make certain that something (usually a future event or condition) will come about.
The new procedures ensure that every shipment is inspected before it leaves the warehouse.
Regular backups ensure that no data is lost if the system fails.
UsageMost often ensure that + clause. Compare insure (protect against loss with insurance) and assure someone (tell them firmly).
Similarguarantee
- 2To make a pledge to someone; to promise or guarantee a person something, or to assure them of it.
Thenne he cryed hym mercy and sayd Faire knyght for goddes loue slee me not / and I shall ensure the neuer werre ageynst thy lady / but be alwey toward her / Thenne Bors lete hym be
1485, Sir Thomas Malory, “xvj”Similarassure
Note
Here the pledge is made to a person rather than about an outcome, and that use has died out. Malory, in Le Morte Darthur of 1485, has a beaten knight beg mercy and promise "I shall ensure the neuer werre ageynst thy lady." The person is the object, the one being promised. Today that work belongs to assure and guarantee, so write assure someone of something, and keep ensure for making an outcome certain.
Checked 6 Nov 2026 · 5 facts
- The personal pledge sense of ensure is obsolete. en.wiktionary.org
- Malory is the author of Le Morte Darthur. gutenberg.org
- Le Morte Darthur was first published in 1485. en.wikipedia.org
- A defeated knight begs mercy and makes the promise to Sir Bors; the person addressed is the object of ensure. gutenberg.org
- The quotation reproduces the historical wording. en.wiktionary.org
Use it in a sentence
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Origin
The root is Old French seur ("sure"); Anglo-Norman built enseurer on it, and that passed into Middle English as ensuren. Insure is a doublet of the same word.