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. (Zoöl.) Without joints, or having the joints indistinct, as some insects.