Synonyms and related words :
able-bodied, athletic, brawny, broad-shouldered, burly, dour, firm, fundamentalist, hard, hidebound, impliable, inexorable, inflexible, iron, ironbound, ironclad, ironhanded, muscular, obdurate, obstinate, orthodox, procrustean, purist, puristic, puritan, puritanic, relentless, rigid, rigorist, rigoristic, rigorous, rockbound, sinewy, stiff, straightlaced, straitlaced, stubborn, thewy, thickset, unbending, uncompromising, unrelenting, unyielding, well-built, well-knit, well-set, well-set-up, wiry