scintilla

noun

Etymology: Existing in English since the 17th century; borrowed from Latin scintilla (“spark”).

1. A small spark or flash.

   “If the action of the electrodynamic waves is so violent that, even without artificial electrification of the secondary conductor, scintillæ occur in its spark-gap, the aluminium leaves remain almost without change.”

2. A small or trace amount.

   “a scintilla of hope”

   “And, if I except the sagacious remark of General Duane which has been so curtly brushed aside, not a scintilla of light has been cast upon these causes by any researches ever published by the Lighthouse Board of Washington.”