(~s, ensuring, ~d)
Frequency: The word is one of the 1500 most common words in English.
To ~ something, or to ~ that something happens, means to make certain that it happens. (FORMAL)
Britain’s negotiators had ~d that the treaty which resulted was a significant change in direction...
...the President’s Council, which ~s the supremacy of the National Party.
VERB: V that, V n