As nouns the difference between flush and irrigation
is that flush
is a group of birds that have suddenly started up from undergrowth, trees etc or flush
can be a sudden flowing; a rush which fills or overflows, as of water for cleansing purposes or flush
can be (poker) a hand consisting of all cards with the same suit while irrigation
is irrigation (the act or process of irrigating).
As a verb flush
is to cause to take flight from concealment or flush
can be to cleanse by flooding with generous quantities of a fluid.
As an adjective flush
is smooth, even, aligned; not sticking out.