fat tail

fat tail (plural fat tails)

1. The relatively high probability of a relatively extreme outcome.
2. (statistics, probability) A tail of a probability distribution with significantly higher kurtosis than a normal distribution (which has kurtosis = 0).
3. (statistics, probability) A tail of a probability distribution with infinite variance.

• (high probability of extreme outcome): heavy tail
• (tail of distribution with positive kurtosis): leptokurtosis

• fat-tailed

• black swan