In music notation, a whole note represents four beats and is represented by an open circle with no stem. It is so named because it lasts for the duration of a whole measure in common time. Also called a semibreve.
A series of whole notes on the staff looks something like this:
/\
---| /-----------------------------------------------------
|/
---/------------------O------------------------------------
/| O O
-/-|/\----------------------------O------------------------
| | |
|--|--|----------------------------------------------------
\ | |
--\|_/-----------------------------------------------------
|
\|