solid ground

NOUN /sɑlɪd_graʊnd/
12 LETTERS · STARTS WITH S

solid ground is a valid 12-letter word worth 14 points in Scrabble and 18 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
S1O1L1I1D2G2R1O1U1N1D2
1 + 1 + 1 + 1 + 2 + 0 + 2 + 1 + 1 + 1 + 1 + 2 =14 PTS
DOUBLE WORD → 28TRIPLE WORD → 42
MEANING

What does solid ground mean?