Why is the ninth month called September?
mid-15c., "belonging exclusively to one person," from Latin peculiaris "of one's own (property)," from peculium "private property," literally "property in cattle" (in ancient times the most important form of property), from pecu "cattle, flock," related to pecus "cattle" (see pecuniary). Meaning "unusual" is first attested c.1600 (earlier "distinguished, special," 1580s; for sense development, cf. idiom). Related: Peculiarly.
as used in the phrase "peculiar people" in 1 Pet. 2:9, is derived from the Lat. peculium, and denotes, as rendered in the Revised Version ("a people for God's own possession"), a special possession or property. The church is the "property" of God, his "purchased possession" (Eph. 1:14; R.V., "God's own possession").