here's the meaning from this website:
http://www.behindthename.com/php/search ... perator=or
BREE
Gender: Feminine
Usage: Irish
Pronounced: BREE
Anglicized form of BRÍGH
BRÍGH
Gender: Feminine
Usage: Irish
Pronounced: BREE
Derived from Irish brígh meaning "power, high".
Also Bree could be a nickname for Breanna or Breana(friends name is this and she goes by Bree)
BREANNA
Gender: Feminine
Usage: English
Pronounced: bree-AN-a
Feminine form of BRIAN
BRIAN
Gender: Masculine
Usage: Irish, English
Pronounced: BRIE-an
The meaning of this name is not known for certain but it is possibly related to the Old Celtic element bre meaning "hill", or by extension "high, noble". Brian Boru was an Irish king who thwarted Viking attempts to conquer Ireland in the 11th century. He was victorious in the Battle of Clontarf, but he himself was slain.