doom-and-gloom

The idiom "doom and gloom" is a relatively modern formation, popularized in the mid-20th century. It combines two powerful, ancient words of Germanic origin: "doom," which evolved from its Old English sense of "judgment" or "decree" to signify an inevitable, often catastrophic fate, and "gloom," which shifted from describing a dark or somber appearance to a state of darkness, melancholy, or depression. The pairing through alliteration ("doom" and "gloom") intensifies the sense of despair, creating a vivid, memorable phrase that encapsulates a pervasive attitude of pessimism and expectation of the worst possible outcome. Its logic lies in the metaphorical linking of a dire final judgment (doom) with the emotional and atmospheric darkness (gloom) that accompanies it.

This is a fixed compound idiom. 'Doom' (Old English dōm, meaning judgment, statute, fate) and 'gloom' (Middle English gloum(b)en, meaning to look sullen or frown) are combined with 'and' to create a new, unified meaning. It functions as a lexicalized unit.