Exact historical dictionary sense
Sector in Webster's 1913 dictionary
The 1913 record labels sector as noun. Its source-bounded etymology and selected historical definition appear below.
[L., properly, a cutter, fr. secare, sectum, to cut: cf. F. secteur. See Section.]
Cross-verified historical senseIn Webster's Revised Unabridged Dictionary (1913), "sector" is labeled noun. Its etymology is recorded as: "[L., properly, a cutter, fr. secare, sectum, to cut: cf. F. secteur. See Section.]" The selected historical definition says: "A part of a circle comprehended between two radii and the included arc."