Emily Dickinson Lexicon

AR-THRO'DI-A, n. [from αρθροω, to frame or articulate.]

1. A species of articulation, in which the head of one bone is received into the shallow socket of another; as the humerus and the scapula. – Encyc.
2. In natural history, a genus of imperfect crystals, found in complex masses, and forming long single pyramids, with very short and slender columns. – Encyc. This word is by mistake used by some authors for arctic.