*aik-

Proto-Indo-European root meaning "be master of, possess." 

It forms all or part of: fraught; freight; ought (v.); owe; own.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit ise "he owns," isah "owner, lord, ruler;" Avestan is- "riches," isvan- "well-off, rich;" Old English agan "to have, own."