letted be known (verb) hint: suggest; indicate
Sinonime: accidental, adventitious, by chance,
contingent,
erratic, extemporaneous, extempore, fluky,
fortuitous, impromptu, improvised,
impulsive,
incidental, infrequent,
irregular,
occasional,
odd, offhand, serendipitous,
spontaneous,
uncertain,
unexpected,
unforeseen, unintentional,
unplanned, unpremeditated
Antonime: deliberate,
painstaking,
planned, premeditated