unpredictable
adjective
uk/ˌʌnprɪˈdɪktəbl/ usif something is unpredictable, it is likely to change suddenly and unexpectedly, so cannot be planned for:
To protect it from the unpredictable nature of software sales, the company has adopted a new business model.
unpredictable effects/events/factors Unpredictable events can have a huge impact on bond values.
It is a very unpredictable market.
The turmoil on Wall Street is emblematic of how the credit mess is spreading in unpredictable ways.
an unpredictable outcome/result
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predictable
unpredictability
noun [ U ]
Stocks carry more risks than bonds because of the unpredictability of corporate profits.
unpredictably
adverb
When share prices go up and down unpredictably, investors tend to sit on their hands.