surface roof of the mouth palate maxilla upper jaw maxillary upper jawbone

pugnacious tough hard-bitten

hard palate surface roof of the mouth oral cavity mouth rima oris tastebud taste bud oral fissure velum soft palate gustatory organ

serious tough thorny problematical demanding rugged difficult touchy challenging knotty rocky embarrassing tricky arduous difficultness hard-fought problematic vexed nasty trying unenviable awkward troublesome fractious baffling effortful elusive sticky herculean tight difficulty tall ticklish ambitious catchy delicate rough

unmerciful tough scheming shrewd insensitive conniving merciless hardened calculating hard-boiled case-hardened difficult calculative steely

hardened hornlike solid adamantine unyielding tumid erect stony stonelike corneous set semihard granitic rocklike woody al dente horny petrous granitelike steely firm hardness

severe strong knockout

heavy effortful punishing operose arduous laborious backbreaking gruelling toilsome grueling

firmly

severely