(by extension, of a problem or task) Very difficult.
Wild boars are also found in mountainous and forest districts.
The dark base of the mountainous thunderheads had a greenish tinge.
In most cases, owing to the mountainous character of the country, horizontal galleries are possible.
Southern Albania, again, is almost wholly mountainous, with the exception of the plains of Iannina and Arta; the most noteworthy feature is the rugged range of the Tchika, or Khimara mountains, which skirt the sea-coast from south-west to northeast, terminating in the lofty promontory of Glossa (ancient Acroceraunia).
Though less mountainous than the other islands, its aspect is barren.