Other forms: ensuring, ensured, ensures
To ensure something is to make sure it actually happens. You check the door twice to ensure it is locked; a recipe tells you to ensure the pan is hot before the fish goes in.
It takes THAT and a whole clause: ensure that everyone has a ticket, ensure that the door closes behind you. In speech people say 'make sure', and ensure belongs to instructions, contracts and reports, where it does the same work in one word. Then there is the trio that trips everybody: ensure means make certain, insure means buy insurance against, assure means tell a person something so they stop worrying. You assure a friend, you insure a car, you ensure a result — and American English blurs ensure and insure, which is why you see both in print. It can also take two objects: one more point would ensure them a place in the final.
1verbensureTo make certain that something happens or is true.
“Please ensure that all the windows are closed before you leave.”
Also accepted in games: guarantee
Ensure arrived from Anglo-Norman enseurer, built on Old French seur, 'sure' — to ensure is to make sure, with the French still showing through. Its twin is insure: the same word entered English twice, and the two of them split the work, one making certain, the other selling policies.
Old French
seur — sure
Anglo-Norman
enseurer
Middle English
ensuren
English, today
ensure
From Middle English ensuren, from Anglo-Norman enseurer, from Old French seur (“sure”). a doublet of insure.
Etymology from Wiktionary, CC BY-SA