νόμου; (nomou) in Romans 3:27: Noun Genitive Singular Masculine

Noun: this form names a concept or reality, here the idea of law or a law-principle in the sentence.

Genitive: the form usually expresses a relationship, such as source, kind, means, or possession, depending on context.

Singular: the form is grammatically singular in this occurrence, pointing to one law in view rather than multiple laws.

Masculine: the noun belongs to the masculine grammatical class, which is a language feature and not a theological claim about gender.

It follows διὰ ποίου and is then echoed by διὰ νόμου πίστεως.

The form is governed by the preposition διὰ and participates in a question about the means or basis by which boasting was excluded.

It functions as the object of the preposition in a genitive phrase, helping specify the kind of law or principle being contrasted.

It does not by itself state the whole meaning of the phrase, and it does not force a single theological category beyond the immediate contrast in the verse.

High: The genitive noun appears in Paul's question about the basis on which boasting is excluded.

Genitive noun governed by διὰ in a contrastive question. asks by what kind of law or principle boasting is excluded. Attached to διὰ ποίου νόμου. Governed by the preposition διὰ and the question word ποίου. The nearby contrast with works and faith determines how law-language functions here.

By what kind of law or principle is boasting excluded' The form belongs to Paul's contrast between a law of works and a law of faith.

Direct: The form directly supports the question by what law and the contrast with law of faith.

Νόμος may be used as law or principle here, so the immediate contrast must govern the explanation. The genitive ending should not force one technical sense of law in every occurrence.

Same lemma must mean exactly the same category every time: The lemma remains νόμος, but the sentence decides whether law-language functions as Mosaic law, principle, or rule.

The witness reads νόμου in Romans 3:27 within the question, διὰ ποίου νόμου; ... ἀλλὰ διὰ νόμου πίστεως.

The lemma νόμος can mean law in general, the Mosaic Law, or a governing principle, so the form must be read from the sentence and not from the lemma alone.

Because the word stands after διὰ, the grammar invites a relationship of means, manner, or basis, and the nearby contrast with τῶν ἔργων and πίστεως helps show that Paul is contrasting kinds of law-language.

In this verse the question is not whether law exists, but what kind of law is in view as the basis on which boasting is excluded.

This fits Paul's broader use of law-language, where context determines whether law means Mosaic law, a principle, or a more general rule.

For readers, the form signals that the phrase should be heard as a relational expression, not as a bare dictionary gloss.

Do not derive from the genitive ending alone that the verse must mean the Mosaic Law, or that the noun changes into a different word or doctrine.