gratissimus
Gratissimus is a Latin adjective meaning "most pleasing," "most agreeable," or "very grateful." It is the superlative form of the adjective gratus, which means "pleasing," "agreeable," or "grateful." As a superlative, gratissimus denotes the highest degree of these qualities.
In classical Latin literature, gratissimus can be used to describe a person, an event, or a feeling.
The adjective is found in various contexts, from personal correspondence to formal orations and historical accounts.