The word "definitely" is an adverb that means something is certain, clear, or without doubt. It is used to express a strong affirmation and indicates that there is no ambiguity about what is being said or decided.
The word "definitely" comes from the Latin word "definitus," which means "to define" or "to set boundaries." The root "define" is derived from "de-" (meaning "down" or "from") and "finire" (meaning "to limit" or "to finish"). This evolved into the Old French "definitif," leading to the English "definite," and later the adverbial form "definitely."