noun

• (countable) A (sudden) flood or inundation of water; specifically, a flood in or overflow of a river or other watercourse due to heavy rain or melting snow; (uncountable, archaic) flooding, inundation.
  "Thys Lepidium that Pliny & Paul [of Aegina] deſcribe⸝ groweth plentuouſly about the water ſyde that rynneth thorow Morpeth in Northumberland⸝ in ſuche places as great heapes of ſtones are caſten together wyth the myght of a great ſpat or flood."
• (countable) A sudden heavy downpour of rain.
  "Doun comes a jaw o' droukin' rain / Upon their honours— / God sends a spate outower the plain, / Or mebbe thun'ers."
• (countable, figurative) A sudden increase or rush of something; a flood, an outburst, an outpouring.
  "Thy rural loves are nature's ſel; / Nae bombaſt ſpates o' nonſenſe ſwell; / Nae ſnap conceits, but that ſweet ſpell / O' witchin love, […]"

verb

• (transitive) To (suddenly) flood or inundate (a river or other watercourse) with water.
  "[H]e paused in a reverie of wilderment and wonder when he could not discern the old fishing-places—they were deeply and darkly flooded for many yards on every side of the spated stream."
• (intransitive) To (suddenly) rain heavily; to pour.