doldrum

Etymology

The noun is possibly derived from dull or Middle English dold (past participle of dullen, dollen (“to make or become blunt or dull; to make or become dull-witted or stupid; to make or become inactive”), from dul, dol, dolle (“not sharp, blunt, dull; not quick-witted, stupid; lethargic, sluggish”); see further at dull), modelled after tantrum. The adjective is probably derived from the noun.