It simply means marrying-out, in contrast to endogamy, or marrying-in.
"Anthropology" by Robert Marett
On the other hand, endogamy is both cause and effect of weakness and proceeds with decline.
"Folkways" by William Graham Sumner
They are monogamy, endogamy, exogamy, Australian marriages, taboo, prohibited degrees, and celibacy.
"The World's Greatest Books - Volume 15 - Science" by Various
What is the relation of endogamy and exogamy (a) to isolation, and (b) to the establishment of a successful stock or race?
"Introduction to the Science of Sociology" by Robert E. Park
Endogamy generally exists where the clan life is little developed, and where relatives know and see little of each other.
"The Sexual Question" by August Forel
Natural selection has determined that exogamy produces fitter progeny than endogamy.
"The Kempton-Wace Letters" by Jack London
There is no antithesis between endogamy and exogamy; no exogamous "tribes" have been found up to the present time.
"The Origin of the Family Private Property and the State" by Frederick Engels
Endogamy also prevails among tribes of Central America.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3" by Various
The Ostiaks regard endogamy (marriage within the clan) as a crime, as do the Yakuts of Siberia.
"Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 1" by Various
There is no strict endogamy within the Khond tribe.
"The Tribes and Castes of the Central Provinces of India" by R. V. Russell