Why is the window open?

why Adverb

— Used to ask the reason for something. Why did you say that? Why did you try to steal money from this shop? — Used to talk about the reason for something. I wonder why he did that. — Used to give more information about the reason for something. Can you tell me the reason why he did that?

why Interjection

— Used to show a person's surprise or impatience about something. Why! Thank you for the present.

why Noun

— (plural: whys) The reason to something. Whenever you begin to write an essay, please do not forget to talk about the who, the what, the when, the where, the why and the how. — (plural: whies) A why is a young cow or woman.

is Verb

— A form of the verb be when talking about someone or something else. He is late for class. Is it hot in here?

the Determiner

— Used, instead of a, to reference something specific, already known to exist. Compare "I read a book." and "I read the book." — Used with a stress, to show that the word following is special. Are you the John Smith that I went to school with? — Used with an adjective that acts like a noun to mean all of the people concerned The poor are always with us. — Used with superlatives forms of adjectives and adverbs. You are the best.

window Noun

— A piece of glass in a wall to let people see through it. He looked out the window.

open Verb

— To move something to the side to allow entrance. I will open the door for our guests. — To prepare for business. She opened the store.

open Adjective

— Having a hole or opening, not closed. The door was open. — Available for business. The shop is open.