The middle point of an hour: The clock chimes on the half-hour. (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "half-hour" in a sentence
"They can even build internal cliffhangers into a half-hour or hour-long program and use the interruptions to their advantage."
"It's been a half-hour since I ordered fries! elle pouvait faire le canard = she might shut her beak! l'équipe (f) = (lunch) crew"
"Yes, because with everything else a truck was blocking the road and so we were stopped for a half-hour or so, and eventually delayed some two hours."