A sharp-toothed wheel inserted into the end of the shank of a spur. (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 "rowel" in a sentence
"They are of blue steel inlaid with strips of silver, and the rowel is a sort of cogged wheel, from an inch and a half to three inches in diameter."
"We all know about her rowel in the White House Administration with Rahm Emanuel, well she seems to be spreading the wealth around."
"Carry the youth to the presence, and I will remain here, with bridle in hand, ready to strike the spurs up to the rowel-heads, in case the hawk flies my way. —"