Someone could mean to say different thing by each of them, but there's hardly any common agreement.

the nomenclature seems to be totally confused

There are contradicting definitions: "dependence: one that is relied on", "dependency: something that is dependent on something else", "dependent: one that is dependent" which also says "archaic : DEPENDENCY" which is certainly the inverse of what is usually meant in technology... is it more correct to install the "dependences"? (wiktionary gives it as the plural)

In the software industry we use "dependency" to refer to the relationship between two objects. We say "looking for dependents" for relationships to dependent things and "looking for dependencies" for relationships to prerequisite things, so it gets that connotation, but the literal meaning is the relationship itself, not the object. Finding a better word is exactly the point of the question

I don't think this is a good overload of 'subtraction'1Olivier Lacan@olivierlacan·Jan 14, 2019Yup. I don’t either.