From oikia; familiar, i.e. (as noun) relatives -- they (them) of (his own) household.
see GREEK oikia
STRONGS NT 3615: οἰκιακόςοἰκιακός (in secular authors and in some N. T. manuscripts also οἰκειακός (cf. εἰ, ἰ) from οἶκος), ὀικιακου, ὁ (οἰκία), "one belonging to the house (Latindomesticus), one under the control of the master of a house," whether a son, or a servant: Matthew 10:36; opposed to ὁ οἰκοδεσπότης, Matthew 10:25. (Plutarch, Cicero, 20.)