1 (of a time) well-chosen or especially favourable or appropriate (an opportune moment).
2 (of an action or event) well-timed; done or occurring at a favourable or useful time.
Derivatives:
opportunely adv. opportuneness n.
Etymology: ME f. OF opportun -une f. L opportunus (as OB-, portus harbour), orig. of the wind driving towards the harbour
Useful english dictionary. 2012.