adj

• (of a river) Marked by frequent variations in water amount (compare flash flood).
  "Flow criteria were used for classification […] The criteria chosen were […] (4) the rate of change of flow with time (logged serial correlation coefficients are 0.2 in flashy rivers, but up to 0.98 in stable ones); and (5) the velocity associated with average daily flows (this varies from 1.03 m/s in flashy rivers to 0.08 m/s in lowland ones)."
• (dated, poetic) Flashing; producing flashes.
  "a flashy light"
• (archaic) Drunk; tipsy.
  "Indeed, he was 'dithguthted' at his condition; and if upon the occasion just described he had allowed himself to be somewhat 'intoxicated with liquor,' I must aver that I do not recollect another instance in which this worthy little gentleman suffered himself to be similarly overtaken. Now and then a little 'flashy' he might be, but nothing more serious—and rely upon it, this was no common virtue in those days."