noun
information, understanding, or skill that you get from experience or education [noncount]
[noncount] :awareness of something :the state of being aware of something
common knowledge
something that many or most people know
public knowledge
something that people know because it has been reported in the news
safe/secure in the knowledge
feeling safe or secure because you know something specified
to someone's knowledge
according to what someone knows - usually used in negative statements
to the best of my knowledge
used to say that you think a statement is true but that there may be something you do not know which makes it untrue