ethnic is derived from the
ἔθνος ethnos (more precisely, from the adjective ἐθνικός ethnikos,
 which was loaned into
Latin as ethnicus). The inherited English language term for this concept is
folk, used alongside the latinate
people since the
late Middle English period.
Early Modern English and until the mid-19th century, ethnic was used to mean
pagan (in the sense of disparate "nations" which did not yet participate in the
oikumene), as the
Septuagint used ta ethne ("the nations") to translate the Hebrew
goyim "the nations, non-Hebrews, non-Jews".
 The Greek term in
early antiquity (
Homeric Greek) could refer to any large group, a host of men, a band of comrades as well as a swarm or flock of animals. In
Classical Greek, the term took on a meaning comparable to the concept now expressed by "ethnic group", mostly translated as "
nation, people"; only in
Hellenistic Greek did the term tend to become further narrowed to refer to "foreign" or "
barbarous" nations in particular (whence the later meaning "heathen, pagan").
In the 19th century, the term came to be used in the sense of "peculiar to a race, people or nation", in a return to the original Greek meaning. The sense of "different cultural groups", and in American English "racial, cultural or national minority group" arises in the 1930s to 1940s,
 serving as a replacement of the term
race which had earlier taken this sense but was now becoming deprecated due to its association with ideological
racism. The abstract ethnicity had been used for "paganism" in the 18th century, but now came to express the meaning of an "ethnic character" (first recorded 1953). The term ethnic group was first recorded in 1935 and entered the Oxford English Dictionary in 1972.
 Depending on the context that is used, the term
nationality may either be used synonymously with ethnicity, or synonymously with
citizenship (in a sovereign state). The process that results in the emergence of an ethnicity is called
ethnogenesis, a term in use in
ethnological literature since about 1950.
Depending on which source of
group identity is emphasized to define membership, the following types of (often mutually overlapping) groups can be identified:
In many cases – for instance, the sense of
Jewish peoplehood – more than one aspect determines membership.