knowl·edge 
/ˈnɑ:lɪʤ/ noun
/ˈnɑ:lɪʤ/ noun 1 : information, understanding, or skill that you get from experience or education [noncount] ▪ She has little/no/some knowledge of fashion/history/cooking. ▪ He has devoted himself to the pursuit of knowledge. ▪ a thirst/quest for knowledge [singular] ▪ a knowledge of carpentry ▪ She gained/acquired a thorough knowledge of local customs. ▪ I have a reading knowledge of French [=I can read French], but I can't speak it fluently. 2 [noncount] : awareness of something : the state of being aware of something
▪ He claimed to have no knowledge of the plan. = He denied all/any knowledge of the plan. ▪ Did you have any knowledge of her intentions? ▪ The decision was made without my knowledge. [=I did not know about the decision]
▪ He claimed to have no knowledge of the plan. = He denied all/any knowledge of the plan. ▪ Did you have any knowledge of her intentions? ▪ The decision was made without my knowledge. [=I did not know about the decision]
common knowledge
: something that many or most people know
▪ It's common knowledge that she plans to run for mayor.
▪ It's common knowledge that she plans to run for mayor.
public knowledge
: something that people know because it has been reported in the news
▪ His legal problems are a matter of public knowledge.
▪ His legal problems are a matter of public knowledge.
safe/secure in the knowledge
: feeling safe or secure because you know something specified
▪ They went on vacation, safe in the knowledge that the farm would be well cared for while they were away.
▪ They went on vacation, safe in the knowledge that the farm would be well cared for while they were away.
to someone's knowledge
: according to what someone knows — usually used in negative statements ▪ “Did anyone arrive late?” “Not to my knowledge.” ▪ No one arrived late to my knowledge. [=I am not aware that anyone arrived late, but it is possible that someone arrived late and I don't know about it]
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 ▪ To the best of my knowledge [=as far as I know], everyone arrived on time. ▪ I answered their questions to the best of my knowledge. [=I gave the best answers I could based on what I knew, but I might have answered differently if I had known something else]
