half-open interval[hăfˈōˌpən, häfˈ-]
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A set of numbers representing all the numbers between a pair of given numbers and including either of the endpoints.