through

Through means in at one side or end and out at another. (preposition)

An example of through is a train traveling the distance of a tunnel.

Through means completely or to the end. (adverb)

An example of through is to see a plan all the way from its conception to its execution.

See through in Webster's New World College Dictionary

See through in American Heritage Dictionary 4

(thro͞o)

preposition

In one side and out the opposite or another side of: went through the tunnel.
Among or between; in the midst of: a walk through the flowers.
By way of: climbed in through the window.
a. By the means or agency of: bought the antique vase through a dealer.
b. Into and out of the handling, care, processing, modification, or consideration of: Her application went through our office. Run the figures through the computer.
Here and there in; around: a tour through France.
From the beginning to the end of: stayed up through the night.
At or to the end of; done or finished with, especially successfully: We are through the initial testing period.
Up to and including: a play that runs through December; a volume that covers A through D.
Past and without stopping for: drove through a red light.
Because of; on account of: She succeeded through hard work. He declined the honor through modesty.

adverb

From one end or side to another or an opposite end or side: opened the door and went through.
From beginning to end; completely: I read the article once through.
Throughout the whole extent or thickness; thoroughly: warmed the leftovers clear through; got soaked through in the rain; a letter that was shot through with the writer's personality.
Over the total distance; all the way: drove through to their final destination.
To a conclusion or an accomplishment: see a matter through.

adjective

Allowing continuous passage; unobstructed: a through street.
a. Affording transportation to a destination with few or no stops and no transfers: a through bus; a through ticket.
b. Continuing on a highway without exiting: through traffic; through lanes.
Passing or extending from one end, side, or surface to another: a through beam.
Having finished; at completion: She was through with the project.
Having no further concern, dealings, or connection: I'm through with him.
a. Having no more use, value, or potential; washed-up: That swimmer is through as an athlete.
b. Doomed to death or destruction.