What does jawless mean?
Jawless means having no jaw or lacking a functional jaw. The word is used especially in biology to describe animals whose mouth structures do not include hinged jaws, such as lampreys, and in medical or anatomical contexts to describe the absence of a jaw. It is more precise than “toothless,” which refers only to the absence of teeth: jawless animals can still possess small tooth-like structures in the mouth. In ordinary discussion, the term is relatively uncommon, but it is useful when distinguishing the basic structure of a mouth from the presence of teeth. Jawless fishes and other jawless vertebrates are often discussed in relation to the early evolution of vertebrate anatomy, since jaws are a major feature that distinguishes many modern vertebrates from primitive lineages.
adjectiveHaving no jaw, or lacking a functional jaw. The term is especially used in zoology to describe jawless animals and in anatomy to describe an abnormal absence of the jaw.
- Having no jaw or jaws, especially in zoological or anatomical contexts.
- Lacking a rigid, hinged mouth structure and therefore unable to bite in the usual way.
"The lamprey is a jawless fish that feeds using a circular, sucker-like mouth."
"Jawless animals such as lampreys belong to an ancient evolutionary lineage."
"The specimen was described as jawless, with a broad, flexible mouth and numerous small teeth."
Lampreys are living reminders that jaws are not essential to an animal’s survival: some have fed for millions of years using a tooth-lined, circular mouth.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does jawless come from?
The word is formed from the English noun “jaw” plus the suffix “-less,” meaning “without.” “Jaw” is an Old English word recorded in Middle English as “jowe” and “jaw,” referring to the bony structure of the lower face and its associated muscles. The modern form and its anatomical sense developed alongside related words such as “jawbone,” “jowl,” and “jawful,” all of which reflect the same basic term for the jaw or lower part of the face.
Related word forms
How jawless is actually used
This is primarily a scientific and descriptive term. It is more specific than “toothless,” because an animal may have teeth without having jaws.
Easily confused with jawless
Toothless means lacking teeth, whereas jawless means lacking a jaw or jaw structure altogether.
Edentulous is a more formal term for lacking teeth, and in biology it can also describe animals traditionally classified as toothless.