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.

1712, "peculiar to a certain language," from Latin idiomaticus, from Greek idiomatikos "peculiar, characteristic;" from idios "one's own" (see idiom) + matos "thinking, animated" (from PIE root *men- (1) "to think"). Meaning "marked by use of idioms" is from 1839.

1640s in reference to qualities of Latin peculiar to writers from Roman Africa (especially Church fathers), from African + -ism. By 1836 as "mode of speech peculiar to African-Americans." From 1957 in reference to the political development of African nations or peoples.

1758, "use of a word or phrase considered peculiar to the Irish," from stem of Hibernia "Ireland" + -ism.

1814, "that which is peculiar to any science, art, etc.," from technical + -ity. Meaning "technical character or quality" is from 1828. Related: Technicalities.

"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]

1713, "odd characteristic or trait," a hybrid from odd + -ity. Meaning "odd person" is recorded by 1748; that of "something old or peculiar" is by 1834.