without question and beyond doubt
"it was decidedly too expensive"
"she told him off in spades"
"by all odds they should win"
Without question and beyond doubt.
"After reviewing all the evidence, I am definitely certain that she is the culprit."
In plain English: Definitely means something is absolutely true or will certainly happen without any doubt.
"I definitely want to go to the party tonight."
Usage: Use definitely to express absolute certainty or confirmation that something is true or will happen. It functions as an intensifier to remove any ambiguity from your statement.
Definitely comes from combining the word definite with the suffix -ly to form an adverb. It entered English by adding a standard grammatical ending to describe something that is done without doubt.