perilous
adjective /ˈperələs/
  /ˈperələs/
 (formal or literary)- very dangerous synonym hazardous
- a perilous adventure/journey
 
Oxford Collocations DictionaryPerilous is used with these nouns:- adventure
 - journey
 - situation
 - …
 
Word OriginMiddle English: from Old French perillous, from Latin periculosus, from periculum ‘danger’, from the base of experiri ‘to try’.