hard coal. anthracite, glance [coal].
harden, v. indurate, solidify; [petrify], ossify, [sear], brutalize, embitter; inure, [season], fortify, [steel], [brace], [accustom].
hardened, a. indurated; [callous], [inexorable], ossified, petrified, obdurate, incorrigible, inveterate, [case-hardened], [seared], depraved, [graceless], [impenitent], confirmed; sclerosed, sclerotic.
hardening, n. induration; habituation, [confirmation]; solidification, [petrifaction], ossification; sclerosis (Med.).
hard-headed, a. [shrewd], astute, [sagacious].
hard-hearted, a. unsympathetic, [inexorable], [ruthless], [unsparing], [stern], obdurate, incompassionate.
hardihood, n. [boldness], [bravery], [courage], intrepidity, fortitude; audacity, effrontery, [impudence].
hard lines. [hardship], difficulties, [adversity].
hardness, n. induration, compactness, impenetrability, solidity, firmness, adamant. Associated word: durometer.
hardship, n. [privation], [adversity], [affliction], [reverse], [calamity], [disaster], visitation.