Perilous, a.
Etymology: [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.
Shades of meaning
Fernald has no entry of its own for perilous; he lists it under precarious.
He lists it without comment; the entries above explain its neighbors.