gratis

This term carries a professional or formal tone, often appearing in commercial, legal, or hospitality contexts. It suggests a deliberate act of generosity or a promotional offer rather than a casual lack of payment. While it is synonymous with free, it implies a specific transaction where a price normally exists but has been waived.

Grammatically, the word functions as both an adjective and an adverb without changing its form. It does not follow standard English inflection patterns for adjectives, meaning it has no comparative or superlative forms.