Definition of malpais in US English:

malpais

noun

US, Regional, South-Western
  • (A) Rugged or difficult country of volcanic origin; a region of bare solidified lava. (b) Basaltic lava.

Origin

Mid 19th century; earliest use found in George Kendall (1809–1867), editor and journalist. From Spanish mal país from malo bad (from classical Latin malus: see mal-) + país country.

Pronunciation

malpais

/malpɑːˈiːs/