Answer: steadiest

AnswerCrossword Clue
STEADIEST

Most reliable

STEADIEST

Most like a rock

STEADIEST

Least skittish.

STEADIEST
Least shaky
STEADIEST
Most firm
STEADIESTMost stable
STEADIESTBest on the balance beam, perhaps
STEADIESTBest on the balance beam, maybe
STEADIESTMost balanced
STEADIESTStill the most?