Synonyms of the word

subsurface

• n. Something that is below the layer that is on the surface.
• n. (countable, mathematics) A surface which is a submanifold of another surface.
• adj. below the surface.

belowground

• adj. beneath the surface of the ground; underground.

submarine

• adj. Undersea.
• adj. Hidden or undisclosed.
• adj. (baseball) Of a pitch, thrown with the hand lower than the elbow.
• n. A boat that can go underwater.
• n. A kind of sandwich made in a long loaf of bread.
• n. (baseball) Pitch delivered with an underhand motion.
• n. Any submarine plant or animal.
• n. (informal) A stowaway on a seagoing vessel.
• v. To operate or serve on a submarine.
• v. To torpedo; to destroy with a sudden sneak attack.

submerged

• v. simple past tense and past participle of submerge.
• adj. underwater.
• adj. below the surface of a liquid.
• adj. hidden.
• adj. poor, impoverished.

submersed

• v. simple past tense and past participle of submerse.

subterranean

• adj. below ground, under the earth, underground.

subterraneous

• adj. Subterranean.

underground

• adj. (not comparable) Below the ground; below the surface of the Earth.
• adj. Hidden, furtive, secretive.
• adj. Of music, art, etc, outside the mainstream.
• adv. Below the ground.
• adv. Secretly.
• n. (chiefly Britain) An underground railway.
• n. (with "the") A movement or organisation of people who resist political convention.
• n. (with "the") A movement or organisation of people who resist artistic convention.
• v. To route electricity distribution cables underground.

undersea

• adj. Existing, relating to, or made for use beneath the sea.

underwater

• adj. (not comparable) beneath the surface of the water, or of or pertaining to the region beneath the water…
• adj. (nautical) beneath the water line of a vessel.
• adj. (figuratively) Under water.
• adj. (finance) having negative equity; owing more on an asset than its market value.
• adv. going beneath the surface of the water.
• n. underlying water or body of water, for example in an aquifer or the deep ocean.
• n. (fishing) A type of lure which lies beneath the water surface.
• v. (agriculture, horticulture) to water or irrigate insufficiently.