1. adverb /ʌndəˈniθ,ʌndɚˈniθ,ʌndɚˈnið/
2. preposition /ʌndəˈniθ,ʌndɚˈniθ,ʌndɚˈnið/
a) Under, below, beneath.
Underneath the water, all was calm.
We flew underneath the bridge.
3. adjective /ʌndəˈniθ,ʌndɚˈniθ,ʌndɚˈnið/
Under, lower.
You can have the underneath bunk.
4. noun /ʌndəˈniθ,ʌndɚˈniθ,ʌndɚˈnið/
a) The part under or lower.
The underneath of the aircraft was painted blue.
b) A background radio sound track played during a specific announcement or program.
The underneath is music from the latest album by [...].
Wikipedia foundation.