Can be a noun,adverb,adjective or verb.
Most definitions are British. Comes from
Etymology Middle English. About the 14th Century. Some 18th Century.
Can mean tips one's hand.Gratuity.. Lots of uses,depends on noun,adverb,verb and adjective. If can also be (used in my business back ground) the short for "The Important Part"
That's all I know..