verb

• (intransitive) To give off sparks; to shine as if emanating sparks; to twinkle or glow.
  "Much interest appears to have been lately excited in England by Dr. Clarke's Experiments on the Blow-pipe, and the dangers of explosion attempted to be guarded against, by various contrivances. The following letter inserted in the Philosophical Magazine for December 1816, will show the importance attached to this interesting application of the gases in promoting fusion. […] 1. Platinum as thick as a stocking wire was instantly fused, scintillated, and fell into a large globule. 2. Palladium fused instantly and slightly scintillated."
• (astronomy) Of a star or other celestial body: to vary rapidly in brightness; to twinkle.
  "Do the stars scintillate at all altitudes? Is there any altitude at which it ceases to manifest itself? At Morges the stars in general scintillate at all altitudes, although feebly near the zenith; but on the nights when the scintillation is very faint, it ceases completely at a zenith distance of 45°."
• (nuclear physics) Especially of a phosphor: to emit a flash of light upon absorbing ionizing radiation.
• (intransitive) To dazzle or to impress.