underneath

What it means

1. not comparableBelow; in a place beneath.

   I can't take my sweater off: I amn't wearing anything else on underneath.

   2 more examples

   I lifted up the pile of clothes, and underneath, on the floor, was a dark red stain.

   connected with it underneath, you see a very fine hair-spring.

   1825, Isaac Taylor, Scenes of British Wealth: In Produce, Manufactures, and Commerce, for the Amusement and Instruction of Little Tarry At-home Travellers

2. not comparableOn 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, Georges Cuvier, translated by Edward Griffith, edited by Georges Cuvier, Edward Pidgeon, and Edward Griffith, The Animal Kingdom: Arranged in Conformity with Its Organization, volume 14, published 2012, →ISBN

In a sentence

I can't take my sweater off: I amn't wearing anything else on underneath.

Where it comes from

1. Proto-Germanic*underniþer
2. Old Englishunderneoþan“underneath”
3. Middle Englishundernethe
4. Englishunderneath

From Middle English undernethe, undernethen, from Old English underneoþan (“underneath”), ultimately from Proto-Germanic *underniþer. Equivalent to under- + neath.