nonobligatory (adjective) discretionary: open to choice
Sinonime: PDQ, at once, away, directly, double-time, first off, forthwith,
immediately, in a flash, instantaneously, instanter, now, on a dime, pronto,
right, right away, spontaneously, straight away, there and then, this minute, tout de suite, without delay
Antonime: eventually, later