protractile

adjective

pro·​trac·​tile prō-ˈtrak-tᵊl 

-ˌtī(-ə)l,

prə-

: capable of being thrust out

protractile jaws

Word History

Etymology

borrowed from New Latin prōtractilis, from Latin prōtrac-, variant stem of prōtrahere "to drag forward, draw or pull out, bring into the open" + -tilis "characterized by (the action of the verb)" — more at protract

First Known Use

1828, in the meaning defined above