Emily Dickinson Lexicon

OP-POR-TUNE, a. [L. opportunus; ob and porto, to bear or bring; probably from the root of fero or porto, to bear. The sense of the verb opporto, would be to bring to or upon. See Import, Importune. In this and all words of like signification, the primary sense is to fall, come or bring to. See Luck, Fortune, Season.]

Properly, having come or being present at a proper time; hence, seasonable; timely; well timed. It agrees with seasonable rather than with convenient, though the sense of the latter may be included in it. Perhaps in view / Of those right confines, whence with neighboring arms, / And opportune excursion, we may chance / Re-enter heaven. Milton.