solid; strong; sturdy; durable; stout
steady; sound; stable; safe (e.g. business); reliable; trustworthy
nucleus; backbone; medium-level; mid-level; main body (of troops); crack troops
strength; solidity; firmness; armour; armor
adhering to (a view, policy, etc.); sticking to; holding fast to; steadfastly maintaining
strong defense; strong defence
firm (market); bullish; strong (sales, economy, etc.); steady; sound
medium-sized enterprise (business, firm)
impregnable fortress; heavily guarded fort
indomitable perseverance; invincible fortitude
(a fortress being) impregnable; unassailable
very cautious (watchful, vigilant); taking every possible precaution
being of firm (unshakable) faith and strict practice
firm and unyielding; rigid
being faithful to one's principles; being of firm purpose and deep commitment; constancy; true blue
of strict morals (moral principles); highly moral
center fielder; centre fielder
firm and solid; stout and durable
strong determination; strong-willed; having strong will power; firmness of purpose
chaste (usu. to one's husband); faithful
dogged perseverance; untiring patience
(the Christian sacrament of) confirmation
sophism; sophistry; quibbling
pachycephalosaur (any dinosaur of infraorder Pachycephalosauria)
firm and solid; sturdy and indestructible; unshakable; adamantine