1590s, "to overhang," also "to provide with shelves," probably a back-formation from shelves, plural of shelf (n.1). Meaning "put on a shelf" first recorded 1650s; metaphoric sense of "lay aside, dismiss" is from 1812. Related: Shelved; shelving.
"to slope gradually," 1610s, from Middle English shelven "to slope," from shelfe "grassy slope," a word related to shelf (n.1). Related: Shelved; shelving.