[adverb] [not gradable]He may possibly decide not to come, in which case there's no problem.Possibly is also used to agree or disagree when some doubt is involved."Do you think this skirt might be too small for her?" "(Very) possibly - she has put on a bit of weight.""Will he come?" "Possibly not."
POSSIBLY
Meaning of POSSIBLY in English
Cambridge English vocab. Кембриджский английский словарь. 2012