Catachresis

The textbook I ordered for my class in idioms and proverbs is rather a mishmash. It has items like "dedo del pie" (toe) as an idiom. That is simply a catachresis*, in my book, like "las patas de la mesa" (the legs of the table.) In Spanish there is no (single) word for toe, rather you say the "finger of the foot."

The book seems to define an idiom as "how you say something in Spanish." So anything over a word in length is an idiom, like "a la izquierda" (on the left). At first I was angry with myself for getting this poor textbook, but don't the students also need to know how to say "toe"? Don't they need to know that you say "las patas de la mesa" and not '"las piernas de la mesa"? Shouldn't I introduce the concept of catachresis? La cara de la moneda...

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*The metaphor for which there is no more literal word in common use. "Tropo que consiste en dar a una palabra sentido traslaticio para designar algo que carece de nombre especial; p. ej., la hoja de la espada; una hoja de papel." We say the "legs of a table" with the implied metaphor from biology, but there is no other, more literal word for this. The face and hands of a clock, the eye of a storm or of a needle, the foot of a mountain, the mouth of a river, the head of a company, the teeth of gears. Most of the examples I can think of use body parts, or the body itself (a body of water). A "root" in the mathematical sense of a "square root" is a catachresis. That's biological but not related to the human body. A sheet of paper is "hoja de papel" or "leaf of paper."

Catachresis also means a mixed or absurd metaphor, but that meaning does not concern me here.