mid-15c., "belonging exclusively to one person," also "special, particular," from Old French peculiaire and directly 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).
The meaning "unusual, uncommon, odd" is by c. 1600 (earlier "distinguished, special, particular, select," 1580s; for sense development, compare idiom). The euphemistic phrase peculiar institution for U.S. slavery is by 1838. Related: Peculiarly.
c. 1600, "exclusive possession, private ownership" (a sense now obsolete); 1640s, "a special characteristic of a person or thing," from peculiar + -ity, or else from Latin peculiaritas. Meaning "quality of being peculiar, individuality" is from 1640s; that of "an oddity" is attested by 1777. Related: Peculiarities.
"embezzle, pilfer, appropriate to one's own use public money or goods entrusted to one's care," 1749, from Latin peculatus, past participle of peculari "to embezzle," from peculum "private property," originally "cattle" (see peculiar). Related: Peculated; peculating; peculator.
"of or peculiar to a (particular) place or country," early 15c., regionale, from Late Latin regionalis "of or belonging to a region or province," from stem of regio (see region). Related: Regionally.
"unvarying tone in music or speaking, utterance at one unvaried pitch," 1640s; see monotony. OED says use of the word as a noun is peculiar to English.
Monotone is a natural device for increasing the sonority of the voice, so that it may readily fill a large space, and is also thought by some to have a peculiar solemnity of effect. It is much used as an element in chanting. [Century Dictionary]