In music notation, a stacatissimo is an articulation mark drawn as a thin carat just above the note-head, or just below it if the stem points upward. It indicates that the note should be played very short and disconnected from the note following it, even more than a staccato -- about one-quarter the duration of the beat. It does not mean that the note should be played louder or more sharply, only more briefly. The word means "very detached" in Italian.
It looks something like this on the staff (complete with time signature and a quarter note scale):
/\
---| /------------------------------|--------------------||
|/ | | ||
---/--------------------------------|---|----|--------v--||
/| 4 | | | | v * ||
-/-|/\----------------------|----|--|---|----|---*---|---||
| | | 4 | | | | | * | | ||
|--|--|----------|-----|----|----|--|--*----^---|----|---||
\ | | | | | * | ^ | | ||
--\|_/-----------|-----|---*----^---|-----------|--------||
| | * ^
\| -*-- ^
^