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Definition of loosejaw
loosejaw
/ˈluːsˌdʒɔː/
loose · jaw
Plural:loosejaws
loosejaw Lexical Profile
CEFR
C2
Grade
12
Tier
3
Usage
Rare
• noun
1
Any of several small, predatory deep-sea fishes of the genus Malacosteus, characterized by a large, specialized lower jaw that lacks an interconnecting membrane, allowing it to snap shut rapidly without water resistance to catch prey.
Example
"The marine biologist explained how the loosejaw utilizes red bioluminescence to illuminate unsuspecting prey before striking with its remarkable mouth structure."
Synonyms
View all synonyms for loosejawWord Origin & Etymology
A descriptive compound of the English words 'loose' and 'jaw', directly referring to the uniquely hinged, open-floor lower jaw of this deep-sea fish.
Usage Trend
Historical frequency of usage in published text.
180019102020
Data source: Google Books Ngram Viewer
Cite this Entry
Wordmom. (2026). Definition of Loosejaw. In Wordmom Dictionary. Retrieved Oct 14, 2026, from https://wordmom.com/dictionary/loosejaw