underwater

adj

1. (not-comparable)Beneath the surface of the water; of or pertaining to the region beneath the water surface.

   “Watch out for underwater obstacles.”

   “He was a pioneer in underwater exploration.”

   “The Chungsha group, also known as Macclesfield Bank, just southeast of the Sisha, consists merely of a group of underwater reefs and sandbanks.”

2. Beneath the water line of a vessel.

   “When the ship was brought into dry dock, it was found that she had underwater damage.”

3. (figuratively)In difficulty, especially financially.
4. Having negative equity; owing more on an asset than its market value.

   “We've been underwater on our mortgage ever since the housing crash.”

   “You're underwater. The best thing you can do is just walk away. Let the bank take it back.”

5. Of an option, having a strike price higher (call options) or lower (put options) than the current market price of the underlying asset or financial product; for example, an option to buy shares at $20 when the current market price is $15.

adv

1. So as to go beneath the surface of the water.

   “Can you swim underwater?”

noun

1. Underlying water or body of water, for example in an aquifer or the deep ocean.
2. A type of lure which lies beneath the water surface.

   “Practically all wobbling underwaters will take fish aplenty in the hands of a man who really knows how to put them through their stints.”

verb

1. (transitive)To water or irrigate insufficiently.

   “Care must be taken not to underwater houseplants in the summer.”

   “If your plant is wilting, this could be another sign of overwatering or underwatering.”