legitimatise

VERB /lɪ'dʒɪtəmə,taɪz/
12 LETTERS · 5 SYLLABLES · STARTS WITH L

legitimatise is a valid 12-letter word worth 15 points in Scrabble and 18 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
L1E1G2I1T1I1M3A1T1I1S1E1
1 + 1 + 2 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 1 + 1 =15 PTS
DOUBLE WORD → 30TRIPLE WORD → 45
MEANING

What does legitimatise mean?