\An*ar"throus\, a. [Gr. 'a`narqros without joints,
without the article; 'an priv. + 'a`rqron joint, the
article.]
1. (Gr. Gram.) Used without the article; as, an anarthrous
   substantive.
2. (Zo["o]l.) Without joints, or having the joints
   indistinct, as some insects.