known
v.v. to have information about something in your mind or to be familiar with a person or place. You use this when you understand a fact or recognize someone you have met before.
v. to possess information through experience or study; to be familiar or acquainted with a person, place, or concept. This past participle form often functions as an adjective to describe things that are recognized or familiar.
I have known my best friend since we were children.
The scientist is widely known for her groundbreaking research on renewable energy sources.
Although the risks were well known to the board of directors, they proceeded with the merger to secure a larger market share.
From Middle English knowen, from Old English cnāwen (past participle). Morphologically know + -n.
Stative verb — rarely used in the continuous (-ing) form. When used as a past participle, it often takes the preposition 'as' or 'for'.
I am knowing him for yearsI have known him for yearsKnow is a stative verb and cannot be used in the continuous form to describe a state that started in the past.