PERILOUS
parlous, perilous, precarious, touch-and-go
(adjective) 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”
Source: WordNet® 3.1
Etymology
Adjective
perilous (comparative more perilous, superlative most perilous)
Dangerous, full of peril.
Source: Wiktionary
Per"il*ous, a. Etym: [OF. perillous, perilleus, F. périlleux, L.
periculosus. See Peril.] [Written also perillous.]
1. Full of, attended with, or involving, peril; dangerous; hazardous;
as, a perilous undertaking.
Infamous hills, and sandy, perilous wilds. Milton.
2. Daring; reckless; dangerous. [Obs.] Latimer.
For I am perilous with knife in hand. Chaucer.
– Per"il*ous*ly, adv.
– Per"il*ous*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition