S: (adj) austere, stern (of a stern or strict bearing or demeanor; forbidding in aspect) "an austere expression"; "a stern face"
S: (adj) grim, inexorable, relentless, stern, unappeasable, unforgiving, unrelenting (not to be placated or appeased or moved by entreaty) "grim determination"; "grim necessity"; "Russia's final hour, it seemed, approached with inexorable certainty"; "relentless persecution"; "the stern demands of parenthood"
S: (adj) stern, strict, exacting (severe and unremitting in making demands) "an exacting instructor"; "a stern disciplinarian"; "strict standards"