Having or resembling a knob or knoblike protuberance. (adjective)
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 "umbonate" in a sentence
"Pileus, scaly or warted.campanulate. silky, cracked or fibrillose.umbonate. umbilicate. striate."
"+Cap+ a golden brown or bright cinnamon color, 1½ to 4 inches broad, umbonate, silky, shining, squamulose, with yellowish fibrils, and then smooth."
"+Cap+ a pale red color, 2 to 3 inches broad, convex when young, then slightly raised in the middle, umbonate, afterward the margin is elevated and the cap becomes funnel-shaped and the margin wavy."