"A determinative factor", "A determinant" and "A decisive factor"

Question

To me, and based on dictionary definitions a "determinative factor", a "determinant" and a "decisive factor", imply a truely "crucial factor" which can lead you to make a decision about something.

Also, I think I can use the noun "determinant" instead of "a determinative factor":

Determinant:

Something that controls or affects what happens in a particular situation:

• Soil and climate are the main determinants of how land is used.
  

Determinative:

1. able to or serving to settle or determine; deciding
   
   2. a factor, circumstance, etc. that settles or determines
      

• A determinative factor influences that are determinative of future behavior.

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Added;
Decisive:

If a fact, action, or event is decisive, it makes it certain that there will be a "particular result". "Strongly affecting" how a situation will progress or end. An action, event etc that is decisive has "a big effect on the way that something develops"; a "decisive factor"/effect/influence etc.

• The economy is regarded as the decisive factor which will determine the outcome of the general election.

Note: for all these terms, we have only one single term in our language which encapsulates all of these meanings.

I wonder if you could tell me more about these three terms.

Answer 1

This NGram graph appears to show that "determinant" is the most widely used term, but single word NGrams almost always occur more frequently than two-word ones. It's not a word that I would use anyway, other than with the mathematical sense, and it does not give the sense of "the most most important factor". For that, you need to say "critical determinant", which does not do so well.

"critical factor" and "determining factor" are the most widely used expressions to convey this meaning.