1) one belonging to the house
2) one under control of the master of a house, whether a son or a servant
Part of Speech: noun masculine
From G3614; familiar, that is, (as noun) relatives: - they (them) of (his own) household.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root οἰκιακός; click on the second column to search for that grammatical form of the root οἰκιακός; click on the third column to search for that word and grammatical form; click on the total to search for the root οἰκιακός.