What are the masculine gender of nouns?

The concept of "masculine gender" for nouns is primarily a feature of grammatically gendered languages, such as French, Spanish, German, and many others. It's not a universal concept across all languages.

In these languages, nouns are assigned a gender (masculine, feminine, or sometimes neuter) and this affects the agreement of articles, adjectives, and other grammatical elements.

For example:

* French: "le livre" (the book - masculine), "la chaise" (the chair - feminine)

* Spanish: "el libro" (the book - masculine), "la silla" (the chair - feminine)

* German: "das Buch" (the book - neuter), "der Stuhl" (the chair - masculine)

However, in languages like English, there is no grammatical gender for nouns. We don't have to use different articles or adjectives based on the perceived gender of the noun.

So, to answer your question directly, "masculine gender" is not a concept that applies to English nouns. It's a feature of certain other languages, but not a universal one.