fat-tailed
|fat-tailed|
/ˌfætˈteɪld/
having a large/heavy tail
Etymology
'fat-tailed' is a compound formed in modern English from 'fat' + 'tail', literally meaning 'having a fat (thick) tail'.
'fat' originates from Old English 'fǣtt'/'fǣt' meaning 'plump' or 'well-fed' and 'tail' originates from Old English 'tægl'/'tægel' (related to Proto-Germanic roots); the compound 'fat-tailed' is a straightforward modern English formation combining the two words.
Initially the components meant 'plump' and 'tail' in the literal, physical sense; over time the compound retained the literal sense but was extended metaphorically in fields like probability/statistics to describe distributions with 'heavy' or 'large' tails (i.e., relatively large probability in extreme outcomes).
Meanings by Part of Speech
Adjective 1
describing a probability distribution whose tails decline more slowly than those of light-tailed distributions (e.g., normal or exponential), so extreme outcomes have relatively high probability.
A fat-tailed distribution assigns higher probability to extreme events than a normal distribution.
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Adjective 2
having a noticeably large or thick tail (used of animals or objects possessing a tail-like part).
The fat-tailed gecko stores fat in its tail to survive lean months.
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Last updated: 2025/10/18 13:51