Impossible to mistake or misinterpret; obvious: unmistakable signs of illness. (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 "unmistakable" in a sentence
"You would have some difficulty in recognising him, though he bears, like the rest of us, what you call the unmistakable Landale stamp."
"Everywhere the socialists proclaimed their coming victory at the ballot-box, while, in unmistakable terms, they stated the situation."
"A certain unmistakable character trait began to manifest itself these early struggling writing days."