Definition of underseal in English:



  • Coat (the underpart of a motor vehicle) with waterproof material as protection against rust.

    • ‘This method determines pavement deflection when undersealing, in accordance with the specifications.’
    • ‘Cars that have been undersealed or wax-oiled are a sure sign that the previous owner was fastidious in their care.’
    • ‘Whilst this was happening Catherine and I were trying to clean and paint the underneath of the car, which seemed to take forever as a previous owner had undersealed the car.’
    • ‘When repainted it was undersealed as well and all rubbers replaced.’
    • ‘You will end up with a smooth shiny surface that is much easier to keep clean than an undersealed one.’
    • ‘The bodies are automatically undersealed and then painted by a combination of manual and machine methods.’
    • ‘The car is also undersealed to protect from the elements.’
    • ‘After caulking has cured, the body is undersealed with an oil-based automotive undercoating for added protection.’
    • ‘I sealed the seams inside the wheelarch with a bitumen sealant and then undersealed the wheelarches.’


mass nounBritish
  • Waterproof coating used as protection against rust.

    • ‘This process uses modern underseals and cavity wax to help prolong the life of the bodyshell and other panels.’
    • ‘I was travelling slowly in a convoy, sedately chipping away at my underseal, when a white van driver decided he would create a bow wave of rocks and a wake of expletives by overtaking the line of traffic at about 60 mph.’
    • ‘By now any competent restorer should know that bitumen underseal is not the product to use.’
    • ‘Fortunately this example has been well looked after, but after 30 years the underseal has failed.’
    • ‘I would be careful with underseal as it can trap water and cause even more rust in the future.’
    • ‘You need to get rid of any flaking underseal first other wise you'll just create pockets for moisture to get trapped in, which will make things worse than leaving it with no protection whatsoever.’