Definition of likely adverb from the Oxford Advanced Learner's Dictionary

likely

adverb
ˈlaɪkli
 
; ˈlaɪkli
 
 
Idioms

as likely as not

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most/very likely

very probably
As likely as not she's forgotten all about it.The illness was caused, most likely, by a virus.

not likely!

(informal, especially British English) used to disagree strongly with a statement or suggestionMe? Join the army? Not likely!
Usage noteUsage note: likelyIn standard British English the adverb likely must be used with a word such as most, more or very:We will most likely see him later. In informal North American English likely is often used on its own:We will likely see him later. He said that he would likely run for President.