A tack with a smooth, rounded head that can be pressed into place with the thumb. (noun)
To affix with a thumbtack. (verb-transitive)
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 "thumbtack" in a sentence
"On a thumbtack was a church calendar with a huge picture of Jesus Christ, his hair brown ringlets against a cerulean-blue background, and his eyes heavenward."
"But there are also more appealing options, such as thumbtack monograms or a dried-bean mosaic of James Brown."
""thumbtack" icon shows the last spot they registered online before disappearing a few days ago while traveling waters off the coast of East Africa."