half-open interval

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A set of numbers representing all the numbers between a pair of given numbers and including either of the endpoints.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics An interval in the real line which contains one of its endpoints but not the other one: i.e., it either contains its supremum or its infimum but not both.