Having no rifling within the barrel. Used of a firearm.(adjective)
A firearm having no rifling.(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 "smoothbore" in a sentence
"I've shot very good groups with Federal TruBalls in smoothbore barrels."
"I've had god luck with the brenneke slugs in smoothbore guns!!!"
"My browning smoothbore is very accurate with remington sluggers. 3 to 4 inch groups at 100 yds."