Not able to be foreseen or known in advance; likely to change or behave in unexpected ways.
From 'predict' (Latin 'praedicere,' to foretell) plus the prefix 'un-' and suffix '-able.' The word is a 20th-century formation, becoming common as science and statistics developed.
Quantum physics shattered the illusion that everything is predictable—subatomic particles genuinely behave unpredictably, following only probability waves. This wasn't ancient philosophy; we only proved it in the 1900s!
Complete word intelligence in one call. Free tier — 50 lookups/day.