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For example, "I've found something [X] in my wall--see how this magnet sticks to it?"

I feel like most people would say "magnetic," but this feels ambiguous since it could imply that object itself has a magnetic field.

I sometimes use the word "ferrous," but this seems not quite right since not all such objects are made of iron. Likewise there's "metal," but not all metals attract magnets.

I've found the term "ferromagnetic," but I'm not sure if that's a general enough term to cover what we in our everyday life experience as "magnetism."

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  • This is more a question about physics than English language. Things that behave this way are either ferromagnetic or ferrimagnetic. Both display spontaneous magnetisation, and without looking into the microstructure, you can't tell which of the two you've found.
    – Divizna
    Jan 9, 2023 at 23:34
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    Yes, ferromagnetism is limited to elements in the first transition group (Fe, Ni, Co), and their alloys and compounds. Jan 9, 2023 at 23:56
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    The magnetism is being induced in the substance in the wall by the permanent magnet you are holding (unless it is another permanent magnet). Once the poles in the substance are aligned by the permanent magnet, there is an attraction due to the magnetic field. There is no real alternative to 'magnetic' as that word describes both permanent magnets and induced magnets.
    – Nigel J
    Jan 10, 2023 at 0:29

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The term is "magnetic materials."

The question is wrong. The term "a magnet" begs the question of their being magnets in the first place.

Materials that can create magnets are, themselves, to given degrees, "magnetic materials."

Thus we have the situation in which a magnetic material may display no obvious signs of magnetism, or be an exceptionally powerful magnet. They are both the same "magnetic material."

The context given is very poor and not ambiguous at all: in the wall there is a magnetic material - it may be magnetised or not, i.e. a magnet or not.

With a known magnet, A, it is exceptionally difficult to say whether what is being attracted is another very weak magnet or simply an unmagnetised piece of magnetic material.

There is more on magnetic materials at https://www.first4magnets.com/magnetic-materials-i156

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This property is known as magnetic permeability.

To quote an article by Dura Magnetics, which explains it better than I can:

By applying an external field, some metal alloys can have a net field created. This created, or induced, field is only present when the external drive field is applied. Once the external drive field is removed, the induced field is also removed.

For example, a permanent magnet is attracted to a ferrous object because magnetism is induced in the object by the magnetic field emanating from the permanent magnet. A magnet is not attracted to materials such as wood because no internal field is induced in the wood. With no induced internal field, there is no field interaction and no attraction.

Two pieces of steel do not attract to each other because they do not induce fields in each other: no field, no interaction, no attraction.

The degree of the induced magnetism is related to the ferrous material’s magnetic permeability, expressed as a unitless value designated by the Greek letter mu (μ). The higher the material’s permeability, the greater the magnetic induction and the resulting force of attraction.

It is useful to compare high magnetic permeability and low magnetic permeability materials to better understand the difference in what magnets are attracted to.

Low permeability materials are materials that are not attracted to a magnet, such as air, wood, plastic, and brass. There is no magnetism induced in them by an external magnetic field. Therefore, they are not attracted by a magnet.

High permeability materials such as ferrous materials, Nickel, and Cobalt alloys have a high permeability. Therefore, magnetic fields can be induced in them when exposed to an external magnetic field.

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