dead certain
No doubt whatsoever
Dead certain means absolutely sure, without any doubt whatsoever.
Dead here functions as an intensifier meaning completely or exactly, as in dead center or dead wrong.
I'm dead certain she was there—I saw her with my own eyes.
The phrase emphasizes that the speaker's certainty admits no possibility of error.
- absoluteTotal, without qualification
- sure thingGuaranteed outcome or agreement
- positiveAffirming or certain
- convincedFirmly believing something
- sureFree from uncertainty
no doubt · undeniable · beyond question · bulletproof · ironclad · guarantee · locked · nailed · sealed · set in stone · stone cold · unwavering · confident · doubtless · unshakeable · rock-solid · airtight · open and shut
- certaintysure, unsure, definite, doubtful, positive
- reliabilityreliable, dependable, trustworthy, consistent, faithful
- affirmationsyes, yeah, yep, okay, sure