Definition of backwash in English:



  • 1[mass noun] The motion of receding waves.

    ‘the backwash is reduced in energy by the percolation of water into the shingle’
    • ‘At 15m a ledge with a boulder-strewn platform extended 30m to the foamy backwash near the cliffs.’
    • ‘Apparently he was swept out to sea by a strong backwash.’
    • ‘The damage was mainly caused by the backwash - waves returning to the sea that sucked back debris from the shore such as trees, cars, sediment and parts of buildings, which broke and overturned corals.’
    • ‘We grasped kelp to anchor us, so as not to be taken out in the backwash, and clambered over its slimy fronds to the jumble of boulders that constituted the beach.’
    • ‘Occasionally, two or three waves stack on top of each other, and the backwash is sucked into the breaking waves, spraying white foam 25 feet into the sky.’
    • ‘Nick finishes another beer, crushes the empty can, and throws it into the backwash.’
    • ‘At the water's edge they would hold hands as the waves would wash up on shore and, in the backwash, suck their heels down into the softened sand.’
    • ‘The beach itself was quite steep, and there was a very severe backwash.’
    • ‘There was an unusually heavy spring tide and a considerable wind at the back of it, so that the backwash was more than usually severe.’
    • ‘‘We believe that she was being swept out to sea by the backwash after going out a little too deep on her own,’ he said.’
    • ‘My toes were gently caressed by the backwash of warm foamy waves, and I followed the strange vibrations of the sound, my ears stuck in a trance.’
    • ‘There was a yellowish-grey foam swirling on top, and after a wave washed up on shore, its backwash collided with the next incoming wave to create a geyser effect.’
    • ‘Following a pounding by incoming waves, coral reefs in shallow water were then raked by a powerful backwash carrying heavy debris, including trees and cars, then covered with smothering sediments.’
    • ‘This is succeeded by plane-bedded sands dipping gently seaward, which are produced by the swash and backwash of the waves on the beach face.’
    • ‘As the roiling backwash streamed past, it scoured around me, and when the froth cleared, there beneath my feet were multitudes of clams, all small and without hydroids.’
    wake, wash, slipstream, backflow
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    1. 1.1A backward current created by an object moving through water or air.
      ‘the backwash of a truck on the autobahn’
      • ‘Because that wasn't the case in the relays, where the field would be widely spread by the time the anchorman hit the water, he had no backwash to contend with - and he could fly.’
      • ‘It is best appreciated in its relaxed, complex entirety, the themes rippling into your consciousness like a cool backwash from a passing ship.’
      • ‘The rotors started to spin up and they hurriedly jumped to the roof a few feet below, ducking to avoid the backwash from the spinning propellers as the copter lifted off the heliport and headed into the night skyline.’
      • ‘On arrival on the apron in Baghdad the pilot shuts down the engines as the hot engine backwash and dust need to be eliminated to maximise casualty comfort and well-being.’
      • ‘As the rig barrelled by and the car shook, I heard the unmistakeable whine of air brakes mixing with backwash.’
      • ‘Very probably the gale of the previous week, and the heavy wind which raged during the night, loosened the supports of the pier, and as soon as the tide came in the backwash found out the weak spots and quickly broke up the whole structure.’
      • ‘We broadside off the backwash from a boulder as big as a house.’
      • ‘The descending shuttle's backwash wasn't helping, either.’
      • ‘I rolled to my feet, turned, and caught the car's backwash full in the face.’
      • ‘The backwash rocked the occupants as the sides of the boats kissed gently.’
      • ‘The air filled with raw power, the backwash sending me skidding back along the corridor.’
      • ‘Here's where it gets good: the guy who threw it hadn't counted on his truck's backwash.’
    2. 1.2The unpleasant after-effects of an event.
      ‘the backwash of the Cuban missile crisis’
      • ‘Gay bookstores are caught in the backwash of an overwhelming tide of commercial consolidation that is swamping most small enterprises, gay and straight.’
      • ‘Part of the backwash, or blowback as the CIA calls it, of globalization is that cultures and regions around the world have rediscovered their own cultural resources.’
      • ‘The challenges facing not only this country, but the world, in the backwash of these events require more than parliamentary parrots squawking on their publicly funded perch.’
      • ‘The emerging issue though, is ensuring some of those already held are not lost in the post-Tampa backwash.’
      • ‘Equity markets - still being fed historic corporate earnings figures and still spooked by the backwash from that affair - remain adrift, unable to find any sustained sense of direction.’
      • ‘And I'd be surprised if some of the backwash of that hasn't carried into the international arena.’
      • ‘The backwash from the affair has spooked investors, concerned that more US corporations may have used flattering accounting methods to overstate their historic profitability.’
      • ‘Many responses contained wit born of desperation amid the backwash created by foot and mouth, BSE and the collapse of tourism.’
      • ‘At the same time he recognizes the commonalities among ethnic groups whose villages straddled national borders and who suffered in the backwash of war.’
      • ‘This is the backwash from the crisis that began in Asia in 1998, has swamped Argentina and is now spreading right across South America.’
      • ‘The figures were seen as a most definite sign yet that the Irish economy was being caught in the backwash of the US slowdown and that Irish growth rates were under severe pressure.’
      • ‘The American newspaper industry is gripped by circulation scandals, and I should not be greatly surprised if the backwash hits Australia.’
      • ‘These arguments reflect the backwash of the decline in the UK's fortune in the immediate postwar world.’
      • ‘Then the country was hit by the backwash of a financial crisis that began in Thailand, on the opposite side of the globe.’
      repercussions, reverberations, after-effects, aftermath, fallout
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    3. 1.3US informal The liquid that flows back into a bottle, glass, etc. after someone has taken a drink, assumed to contain that person's saliva.
      ‘Can you please stop drinking straight from the milk carton? I don't want your backwash!’
      • ‘He wakes up, downs the backwash left in a cheap beer bottle, and dons his pilot gear.’
      • ‘Yup, our own scuzzy mouth backwash provides the bacteria.’
      • ‘I don't want to dismiss the social code entirely, but any true medical fears from backwash are utterly overrated.’
      • ‘It was a late dinner for us so the salsa was probably sitting there all day; we likely had the 'backwash' of it.’
      • ‘Terry and Alice share a beer glass for some bizarre reason (am I the only one who fears backwash?)’
      • ‘If you enjoy carrot juice and don't mind a little bit of backwash, contact me and I'll hook you up with the rest of the bottle.’
      • ‘Did the bartender actually clean your seemingly fresh beer mug or just rinse it behind the bar in a tub filled with the backwash of strangers?’
      • ‘I hope you don't mind but my coworkers took sips so there are a few more speckles of backwash in it now.’


  • Clean (a filter) by reversing the flow of fluid through it.

    ‘the very fine mesh is backwashed to remove solids’
    • ‘There is also one backwash pump that is used to backwash the filters.’
    • ‘The backwash valve opens to backwash the filters.’
    • ‘The sludge generated from backwashing the filters is sent to a spent washwater tank for recirculation through the facility to minimize waste.’
    • ‘‘When we shut down the machine,’ he observed, ‘it backwashes itself to prevent potential problems with dried ink.’’
    • ‘The filters are backwashed every 24 hours to keep them clean.’