taru-adjective, adverb taking the 'to' particle
Archaic literary word describing a bleak, lonely, or desolate atmosphere or state. Used as a taru-adjective or adverb with と.
In old novels, the expression 'a desolate landscape' appears.
He was drinking alone, feeling lonesome and dreary.
forlorn and helpless; lonely and desolate
desolate and forlorn scene
The exact derivation is uncertain; the kanji 落 (fall) and 莫 (vast/desolate) combine to suggest a fallen, empty state. The reading らくばく is a Sino-Japanese on'yomi compound.