by trial and error

ADVERB
18 LETTERS · STARTS WITH B

by trial and error is a valid 18-letter word worth 21 points in Scrabble and 23 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
B3Y4T1R1I1A1L1A1N1D2E1R1R1O1R1
3 + 4 + 0 + 1 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 2 + 0 + 1 + 1 + 1 + 1 + 1 =21 PTS
DOUBLE WORD → 42TRIPLE WORD → 63
MEANING

What does by trial and error mean?

ADVERB · 1 SENSE
1

In an empirical manner.