lose one's temper

VERB
17 LETTERS · STARTS WITH L

lose one's temper is a valid 17-letter word worth 18 points in Scrabble and 22 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
L1O1S1E1O1N1E1'0S1T1E1M3P3E1R1
1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 0 + 1 + 0 + 1 + 1 + 3 + 3 + 1 + 1 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does lose one's temper mean?