Unmistakable means impossible to confuse with anything else. You know what it is the moment you meet it.
It attaches to sounds, smells and signs above all: an unmistakable smell of burning, the unmistakable sound of his voice, unmistakable signs of damp. The word is a compliment when applied to style, since an unmistakable style is one nobody else has. It is often spelled unmistakeable with an e, and both forms are accepted. The adverb unmistakably usually props up an adjective.
1adjectiveunmistakableSo distinctive that it cannot be confused with anything else.
“There was an unmistakable smell of paint.”
Old Norse
mistaka — to take in error, to miscarry
Middle English
mistaken
English
mistake
English, today
unmistakable
From un- + mistake + -able. mistake comes from Middle English mistaken, from Old Norse mistaka (“to take in error, to miscarry”); equivalent to mis + take. Cognate with Icelandic mistaka (“to mistake”), Swedish missta (“to mistake”) (before apocope misstaga). The noun, which replaced earlier mistaking, is derived from the verb. Compare Swedish misstag (“mistake”), Faroese mistak (“mitake”), Icelandic mistak (“mistake”).
Etymology from Wiktionary, CC BY-SA