solid as rock (adjective) constant: fixed
Sinonime: connected,
consistent,
continual, equable,
even,
firm,
habitual,
homogeneous,
immutable, invariable, like the Rock of Gibralter, monochrome, monophonic,
monotonous, nonstop, of a piece,
permanent,
perpetual,
regular, regularized, solid as rock, stabile,
stable, standardized,
steadfast,
steady,
together, unalterable, unbroken,
unchanging, unflappable, unfluctuating,
uniform, uninterrupted, unvarying
Antonime: changeable,
fickle, fluctuating, inconstant,
irregular,
unstable, unsteady,
varying,
wavering