one of the hoary word riddles one hears (too) often as a word maven is, "What are the four words in the English language ending in -dous?" (you must amend this to 'four common words' in order to avoid a pedantic word dump from some surly word mavens.)

just this afternoon I encountered another such, rescued from the Dustbin of Obsolete Words: jeopardous (last found in the wild by Murray in 1661, but used otherwhence since): jeopardous - Fraught with risk or danger; hazardous, risky, perilous, dangerous.

"In such snow he'd have led us into all sorts of thrilling and jeopardous traps..."
- Leif Enger, Peace Like a River (2002)

Enger actually goes on to use the word again:
"Had the man not opted for a late soak my brother's career might've ended on the spot, but wet feet and wood floors make jeopardous allies..." - ibid

I think it's a word that warrants wider use.

-tsuwm