adj. not secure; beset with difficulties; "a shaky marriage"

adj. fraught with danger; "dangerous waters"; "a parlous journey on stormy seas"; "a perilous voyage across the Atlantic in a small boat"; "the precarious life of an undersea diver"; "dangerous surgery followed by a touch-and-go recovery"

adj. liable to rock; "on high rocky heels"

adj. (of the voice) quivering as from weakness or fear; "the old lady's quavering voice"; "spoke timidly in a tremulous voice"

adj. vibrating slightly and irregularly; as e.g. with fear or cold or like the leaves of an aspen in a breeze; "a quaking bog"; "the quaking child asked for more"; "quivering leaves of a poplar tree"; "with shaking knees"; "seemed shaky on her feet"; "sparkling light from the shivering crystals of the chandelier"; "trembling hands"

adj. lacking stability or fixity or firmness; "unstable political conditions"; "the tower proved to be unstable in the high wind"; "an unstable world economy"

adj. liable to sudden unpredictable change; "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next"

adj. lacking in security or safety; "his fortune was increasingly insecure"; "an insecure future"

adj. threatening or foreshadowing evil or tragic developments; "a baleful look"; "forbidding thunderclouds"; "his tone became menacing"; "ominous rumblings of discontent"; "sinister storm clouds"; "a sinister smile"; "his threatening behavior"; "ugly black clouds"; "the situation became ugly"

adj. concerned with work or important matters rather than play or trivialities; "a serious student of history"; "a serious attempt to learn to ski"; "gave me a serious look"; "a serious young man"; "are you serious or joking?"; "Don't be so serious!"

adj. of an instrument or device; capable of registering minute differences or changes precisely; "almost undetectable with even the most delicate instruments"

adj. causing or fraught with or showing anxiety; "spent an anxious night waiting for the test results"; "cast anxious glances behind her"; "those nervous moments before takeoff"; "an unquiet mind"

adj. physically or mentally ill at ease: "ill at ease with strangers"; "felt strange in the presence of men who talked excitedly of ... battle"

adj. moving at very high speed; "a breakneck pace"

adj. of uncertain outcome; especially fraught with risk; "an extremely dicey future on a brave new world of liquid nitrogen, tar, and smog"- New Yorker

adj. showing extreme courage; especially of actions courageously undertaken in desperation as a last resort; "made a last desperate attempt to reach the climber"; "the desperate gallantry of our naval task forces marked the turning point in the Pacific war"- G.C.Marshall; "they took heroic measures to save his life"

adj. able or likely to do harm

adj. involving risk or danger; "skydiving is a hazardous sport"; "extremely risky going out in the tide and fog"; "a wild financial scheme"

adj. intended to entrap

adj. caught in a difficult or dangerous situation; "there I was back on the hook"

adj. dangerous to yourself or your interests; "suicidal impulses"; "a suicidal corporate takeover strategy"; "a kamikaze pilot"

adj. dangerously unstable and unpredictable; "treacherous winding roads"; "an unreliable trestle"

adj. free from danger or the risk of harm; "a safe trip"; "you will be safe here"; "a safe place"; "a safe bet"