coral reef (noun) reef: underwater or partially submerged ledge
Sinonime: adamant,
constant, dead set on, dug in,
fast,
firm, hard-nosed, immobile, immotile,
immutable,
impassive,
inflexible,
intransigent, locked in,
motionless,
obdurate,
quiescent,
resolute,
rooted,
secure,
set, set in concrete, set in stone,
solid,
stable, stand pat,
stationary,
steadfast, stick to guns,
stuck, tough nut, unalterable, unchangeable,
uncompromising, unmodifiable, unshakable,
unwavering,
unyieldingAntonime: mobile, movable,
moving, unfixed