one say (noun) opportunity: lucky chance; favorable circumstances
Sinonime: according to pleasure, ad libitum, as one thinks best, as one wishes, at will,
extemporaneous, extempore, extemporize, extemporized, impromptu,
improvise, improvised, made-up, off-the-cuff, off-the-cuff, spontaneous, unprepared, unrehearsed, without restraint
Antonime: deliberate,
planned,
prepared, rehearsed,
written