Frightening because of an awareness of danger.

Roget 860: fearing etc. v.; frightened etc. v.; in fear, in a fright etc. n.; haunted with the fear of etc. n.; afeard^†.    afraid, fearful; timid, timorous; nervous, diffident, coy, faint-hearted, tremulous, shaky, afraid of one's shadow, apprehensive, restless, fidgety; more frightened than hurt.    aghast; awe-stricken, horror-stricken, terror-stricken, panic-stricken, awestruck, awe-stricken, horror-struck; frightened to death, white as a sheet; pale, pale as a ghost, pale as death, pale as ashes; breathless, in hysterics.    inspiring fear etc. v.; alarming; formidable, redoubtable; perilous etc. (danger) 665; portentous; fearful; dread, dreadful; fell; dire, direful; shocking; terrible, terrific; tremendous; horrid, horrible, horrific; ghastly; awful, awe-inspiring; revolting etc. (painful) 830; Gorgonian.    ... show more

Roget 665: in danger etc. n.; endangered etc. v.; fraught with danger; dangerous, hazardous, perilous, parlous, periculous^†; unsafe, unprotected etc. (safe, protect) etc. 664; insecure.    untrustworthy; built upon.   sand, on a sandy basis; wildcat.    defenseless, fenceless, guardless^†, harborless; unshielded; vulnerable, expugnable^†, exposed; open to etc. (liable) 177.    aux abois [Fr.], at bay; on the wrong side of the wall, on a lee shore, on the rocks.    at stake, in question; precarious, critical, ticklish; slippery, slippy; hanging by a thread etc. v.; with a halter round one's neck; between the hammer and the anvil, between Scylla and Charybdis, between a rock and a hard place, between the devil and the deep blue sea, between two fires; on the edge of a precipice, on the brink of a precipice, on the verge of a precipice, on the edge of a volcano; in the lion's den, on slippery ground, under fire; not out of the wood.    unwarned, unadmonished, unadvised, unprepared etc. 674; off one's guard etc. (inexpectant) 508^†.    tottering; unstable, unsteady; shaky, top-heavy, tumbledown, ramshackle, crumbling, waterlogged; helpless, guideless^†; in a bad way; reduced to the last extremity, at the last extremity; trembling in the balance; nodding to its fall etc. (destruction) 162.    threatening etc. 909; ominous, illomened; alarming etc. (fear) 860; explosive.    adventurous etc. (rash) 863, (bold) 861.    ... show more

Dutch: alarmerend, zorgwekkend