Ensure vs. insure (vs. assure)

Because of their similar sound, ensure and insure are often confused with each other—and assure is often thrown into the mix as well. All three words have distinct meanings with little crossover between them.

insure

Insure usage is simple: it means to provide insurance for or to have insurance for. In modern English, it has no meaning beyond this. Thus, this usage is incorrect:

To insure that regular checks occur, the department installed electronic checkpoints with bar codes around the jail . . . [LA Times]

And this is correct insure usage:

Citizens was formed to cover property owners who can’t find a private company willing to insure them. [Miami Herald]

ensure

Ensure means to make sure or certain. These are correct:

Working together as a team and under Red’s direction, we will ensure that this project will make all Texans very proud and will benefit our great state. [qtd. in NYT]

President Barack Obama said on Wednesday he would fight to ensure U.S. exporters had a level playing field to compete for world trade . . . [Reuters]

assure

Assure means to inform positively or to cause to be sure—for example:

Officials scrambled to assure Pakistan that the administration doesn’t condone the leak of 76,000 Afghan war documents by Web site WikiLeaks . . . [WSJ]

Assure is often mistakenly used where ensure would be more appropriate—for example:

The way he frames the challenges facing the budget pretty much assure that conclusion. [The Heritage Foundation]

Periodic meetings of the chairpersons of all of these district evaluation teams in the state should occasionally hold meetings to assure that everyone involved understands what is expected of them and are operating accordingly. [The Baltimore Sun]