Without bones; boneless, or relating to the removal of bones.
From Latin 'ex-' (out/without) + 'os' (bone) + '-eous' (characterized by). A medieval anatomical term rarely used in modern English except in specialized medical or zoological contexts.
Jellyfish, octopuses, and worms are naturally exosseous creatures—they never had bones to begin with, which is why they can squeeze through impossibly tiny spaces.
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