The term "gmail" functions as a proper noun. As a proper noun, it designates a specific, unique entity: the email service provided by Google. This classification distinguishes it from a common noun like "email," which refers to a general class of electronic messaging systems, by identifying a particular, branded instance.
The classification is based on its role as a brand name and a registered trademark. Proper nouns, by definition, name specific people, places, organizations, or brands and are conventionally capitalized in written English ("Gmail"). Although the term is sometimes used colloquially as a verb through a process called anthimeria (e.g., "I'll gmail you the document"), its primary and formal grammatical category remains a noun. Furthermore, it frequently acts as a noun adjunct (or attributive noun) to modify other nouns, as seen in phrases like "Gmail account" or "Gmail interface."
In practice, its status as a proper noun governs its syntactical use. It requires capitalization in formal writing and can function as the subject of a sentence ("Gmail is a popular service."), a direct object ("He checked his Gmail."), or the object of a preposition ("The file was sent through Gmail."). Its use as a noun adjunct allows it to specify and qualify other nouns, providing clarity and precision by linking them directly to the specific service.
