Today was the first time that the dictionary on my Kindle came in handy.  I was reading Niditch’s War in the Hebrew Bible: A Study in the Ethics of Violence and came across the words “endogamy” and “exogamy.”  Should have been able to figure those out based on prefixes and root, but it was early.  So, I used the Kindle word look-up feature (I figured out exogamy after reading the definition of endogamy, but I’ll give you both definitions anyway):

Endogamy: en-dog-a-my n. [ANTHROPOLOGY] the custom of marrying only within the limits of a local community, clan, or tribe. Compare with EXOGAMY.

Exogamy: ex-og-a-my n. [ANTHROPOLOGY] the custom of marrying outside a community, clan, or tribe. Compare with ENDOGAMY.