steady as a rock
Firm, dependable, as in Betty always knows her part; she's steady as a rock. This simile uses rock in the sense of “something that affords a sure support,” a usage dating from the early 1500s.
Words nearby steady as a rock
stead,
steadfast,
steadicam,
steading,
steady,
steady as a rock,
steady state,
steady state theory,
steady state universe,
steady-going,
steady-handed