A monstrosity is something very large and ugly. People most often say it about a building: a huge, clumsy block that spoils the street or the view. You can also use it for an object, a machine, a plan, or even a piece of writing that feels oversized and wrong. It sits in the same family as monster and monstrous, but in everyday talk it is usually not a scary creature from a story — it is the ugly thing itself. The word is strong and unkind; you say it when you dislike how something looks, not when you are being careful and polite. Newspapers use it about architecture; ordinary speakers use it as a complaint.