Emily Dickinson Lexicon

KEY, n.² [Ir. ceigh; D. kaai; G. kai; Fr. quai; Arm. qae. The word is probably contracted from the root of the preceding word, signifying, to hold, make fast, restrain. Class Cg.]

A bank or wharf built on the side of a river or harbor, for the convenience of loading and unloading ships, and securing them in their stations. Hence, keys are furnished with posts, rings, cranes, capstans, &c. It sometimes written Quay. – Encyc.