reference frame

NOUN /rɛfərəns_freɪm/
15 LETTERS · STARTS WITH R

reference frame is a valid 15-letter word worth 24 points in Scrabble and 27 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1E1F4E1R1E1N1C3E1F4R1A1M3E1
1 + 1 + 4 + 1 + 1 + 1 + 1 + 3 + 1 + 0 + 4 + 1 + 1 + 3 + 1 =24 PTS
DOUBLE WORD → 48TRIPLE WORD → 72
MEANING

What does reference frame mean?