What is the reason that the things that you put on bolts came to be called nuts. There seems to be little similarity to the nuts that we eat.
There is also no relationship between an indehiscent, hard-shelled, one-loculated, one-seeded fruit, such as an acorn or a hazelnut, and:
- A crazy or eccentric person.
- An enthusiast; a buff (a movie nut).
- A difficult endeavor or problem (painting the closet was a tough nut to crack).
- The human head.
- A ridge of wood at the top of the fingerboard or neck of a stringed instrument, over which the strings pass.
- The cost of launching a business venture.
- The operating expenses of a theater, theatrical production, or similar enterprise.
- The testicles.
Yet they are all definitions of the same word. I think this is just a simple example of a homograph.
Umm…“tough nut to crack” sounds like a fairly accurate metaphor for “difficult” to me…
I could see that a bag or handful of hex (or the earlier square) nuts could be likened to a bag or handful of nuts from a tree. They’re little hard things about yea so big. I don’t know when cap nuts first came along, but they DO look more like little tree nuts --to me, anyway.
I actually never wondered much about why they call them “nuts” —I have wondered how the other things came to be called “washers”, though.
This site has a rather generic response.
Rather non-specific, but maybe a steer/nut in the right direction?