underneath UK /ˌʌndəˈniːθ/US /ˌʌndɚˈniθ/preposition 2adverb 2noun 2adjective 1forms 1 preposition2 •in the space below somethingUnderneath the water, all was calm.We flew underneath the bridge. •Under the control or power of.There was little freedom underneath the Nazi jackboot. adverb2 •Below; in a place beneath.I can't take my sweater off: I amn't wearing anything else on underneath.I lifted up the pile of clothes, and underneath, on the floor, was a dark red stain. •On the underside or lower face.No insects exhibit, like them, what may be termed four net-work eyes. It is very easy to perceive them in looking at the animal from above, and then examining it underneath — 1832 noun2 •The bottom of something.The underneath of the aircraft was painted blue. •A background radio sound track played during a specific announcement or program.The underneath is music from the latest album by …. — 2009 adjective1 •Under, lower.You can have the underneath bunk.The underneath part is harder to reach. formsunderneaths