Merriam-Webster's Dictionary and Thesaurus - Merriam-Webster [1483]
[1] callous, cold-blooded, hard, heartless, inhuman, inhumane, merciless, obdurate, pitiless, ruthless, soulless, stony, uncharitable, unfeeling, unsympathetic—more at HARD
[2] bountiful, charitable, free, generous, liberal, munificent, openhanded, unselfish—more at GENEROUS
un·speak·able adjective 1 : impossible to express in words
2 : extremely bad
— un·speak·ably adverb
Synonyms
indescribable, ineffable, inexpressible, nameless, unutterable—more at INDESCRIBABLE
un·spec·i·fied adjective : not specified
Synonyms
anonymous, certain, one, some, unidentified, unnamed—more at CERTAIN
un·spo·ken adjective 1 : not spoken or uttered
2 : not spoken to or addressed
3 : not speaking
Synonyms
implicit, tacit, unexpressed, unvoiced, wordless—more at IMPLICIT
un·sports·man·like adjective : not sportsmanlike : not characteristic of or exhibiting good sportsmanship
Synonyms
dirty, foul, illegal, unfair
un·spot·ted adjective : not spotted or stained; especially : free from moral stain
un·sprung adjective : not sprung; especially : not equipped with springs
un·sta·ble adjective 1 a : not stable : not steady in action or movement
b : lacking steadiness : apt to move, sway, or fall
2 : wavering in purpose or intent : FICKLE; also : lacking effective emotional control
3 : readily changing (as by decomposing) in chemical or physical composition or in biological activity Synonyms [1a] erratic, irregular, unequal, uneven, unsteady—more at UNEVEN [2] capricious, changeable, fickle, inconstant, mercurial, temperamental, unpredictable, unsettled, unsteady, volatile—more at FICKLE un·stained adjective 1 : not stained or discolored : not spotted 2 : not morally blemished or stained un·stead·i·ness noun : the quality or state of being unsteady Synonyms insecurity, instability, precariousness, shakiness—more at INSTABILITY un·steady adjective : not steady : UNSTABLE — un·stead·i·ly adverb Synonyms casual, choppy, discontinuous, erratic, fitful, intermittent, irregular, occasional, spasmodic, sporadic, spotty—more at FITFUL erratic, irregular, unequal, uneven, unstable—more at UNEVEN un·stint·ing adjective 1 : not restricting or holding back 2 : giving or being given freely or generously <~ praise> un·stop verb 1 : to free from any obstruction : UNCLOG 2 : to remove a stopper from Synonyms clear, free, open, unclog un·stop·pa·ble adjective : incapable of being stopped un·strap verb : to remove or loose a strap from un·stressed adjective : not stressed; especially : not bearing a stress or accent un·struc·tured adjective : lacking structure or organization : not formally organized in a set or conventional pattern Synonyms amorphous, formless, shapeless, unformed, unshaped—more at FORMLESS un·strung adjective 1 : having the strings loose or detached 2 : made weak, disordered, or unstable un·stud·ied adjective 1 : not acquired by study 2 : NATURAL, UNFORCED un·styl·ish adjective : not stylish Synonyms dowdy, inelegant, tacky, tasteless, trashy, unfashionable—more at TACKY un·sub·stan·tial adjective : not substantial : lacking substance, firmness, or strength Synonyms flimsy, gauzy, insubstantial—more at FLIMSY bodiless, immaterial, incorporeal, insubstantial, nonmaterial, nonphysical, spiritual—more at IMMATERIAL un·sub·stan·ti·at·ed adjective : not substantiated; especially : not supported or borne out by fact Synonyms baseless, groundless, invalid, unfounded, unreasonable, unsupported, unwarranted—more at BASELESS un·suc·cess·ful adjective : not successful : not meeting with or producing success Synonyms abortive, bootless, empty, fruitless, futile, ineffective, unavailing, unproductive, useless, vain—more at FUTILE un·suit·able adjective : not suitable or fitting Synonyms graceless, improper, inapt, incongruous, incorrect, indecorous, inept, infelicitous, unbecoming, unfit, unhappy, unseemly, wrong un·sul·lied adjective