perilous

English

From Middle English perilous, from Old French perilleus, equivalent to peril +‎ -ous, from the noun peril, or from Latin perīculōsus. Doublet of periculous.

perilous (comparative more perilous, superlative most perilous)

Dangerous, full of peril.
- 1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887, →OCLC:
  Three miles or more to our starboard is a low dim line. It is the Eastern shore of Central Africa. We are running to the southward, before the North East Monsoon, between the mainland and the reef that for hundreds of miles fringes this perilous coast.
- 1963, Lester del Rey, The Sky Is Falling:
  The effects are already being felt. Gamma radiation is flooding through the gaps; the quick-breeding viruses are mutating through half the world, faster than the Medical Art can control them, so that millions of us are sneezing and choking—and dying, too, for lack of antibiotics and proper care. Air travel is a perilous thing; just today, a stratosphere roc crashed head-on into a fragment of the sky and was killed with all its passengers.

imperil
peril
Category English terms derived from the Proto-Indo-European root *per- (risk) not found

dangerous, full of peril

perilous (plural and weak singular perilouse, superlative perilousest)

Full of danger or peril; dangerous, harmful, periculous:
1. Fatal, mortal; potentially resulting in death.
2. Scary, frightening; inducing horror and psychological damage.
3. (Late Middle English) Religiously harmful or hurtful
4. (Late Middle English) Unfortunate; experiencing bad luck.

“perilǒus, adj.”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007, retrieved 15 July 2018.