scintilla

noun

definition: a tiny amount; trace.
example: There was not a scintilla of truth in the rumor.

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Note:

“Scintilla” is usually used in negative constructions, as in “not a scintilla of…,” and frequently to convey a complete lack of truth, evidence, or proof.
“Scintilla” is a Latin word meaning “spark, particle of fire, atom.”  The English verb “scintillate” retains the fiery element and can mean “to give off sparks” (literally) or “to sparkle intellectually.” 

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