Wiktionary
n. 1 (context US English) a permit to be out of class during school hours. 2 (context by extension informal English) a wife's permission for her husband to go for a night out with friends.
WordNet
n. written permission from a teacher for a student to be out the classroom and in the halls of the school
Wikipedia
Hall Pass is a 2011 American comedy film produced and directed by the Farrelly brothers and co-written by them along with Pete Jones, the writer/director of Stolen Summer. It stars Owen Wilson and Jason Sudeikis. It was theatrically released on February 25, 2011. The film received mixed critical reviews and was a moderate box office success by grossing over $83 million.
Usage examples of "hall pass".
I was halfway to the door when it occurred to me I was no longer a high school student without a hall pass.
Miss Shepherd handed her a hall pass and patted Mollie on the shoulder.
COLENE had a study hall during the last period, and as an Honor student she had a regular hall pass.