Frequency: The word is one of the 3000 most common words in English.
1.
Someone who is ~ is very confident and relaxed.
He was infinitely more ~ than in his more recent parliamentary appearances.
ADJ
~ness
This a lyrical work written with the authority and ~ness of an experienced writer.
= assurance
N-UNCOUNT
2.
If something is ~, it is certain to happen.
Our victory is ~; nothing can stop us...
? uncertain
ADJ: v-link ADJ
3.
If you are ~ of something, you are certain to get it or achieve it.
Laura Davies is ~ of a place in Europe’s team...
ADJ: v-link ADJ of n
4.
If you say that someone can rest ~ that something is the case, you mean that it is definitely the case, so they do not need to worry about it.
Their parents can rest ~ that their children’s safety will be of paramount importance...
PHRASE: PHR that, PHR with cl emphasis