reason.

-In what way or manner; by what means? How did the accident happen?
-To what extent, degree, etc.?: How damaged is the car?
-In what state or condition?: How are you?
-For what reason; why?: How can you talk such nonsense?
-To what effect; with what meaning?: How is one to interpret his action?
-What?: How do you mean? If they don't have vanilla, how about chocolate?
-(Used as an intensifier): How seldom I go there!
-By what title or name?: How does one address the president?
-At what price: How are the new cars going, cheaper than last year's models?
-By what amount or in what measure or quantity?: How do you sell these tomatoes?
-In what form or shape?: How does the demon appear in the first act of the opera? How does the medication come?
Conjunction
-The manner or way in which: He couldn't figure out how to solve the problem.
-About the manner, condition, or way in which: I don't care how you leave your desk when you go. Be careful how you act.
-In whatever manner or way; however: You can travel how you please.
-Informal that He told us how he was honest and could be trusted.
Noun
-A question concerning the way or manner in which something is done, achieved, etc.: a child's unending whys and how’s.
-A way or manner of doing something: to consider all the how’s and wherefores.
-A word formerly used in communications to represent the letter H.
Idioms
-And how! Informal. certainly! you bet!: Am I happy? And how!
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