a-part' (badh, "separation," i.e. alone, by oneself; niddah, "uncleanness" i.e. something put away: "an abomination"): In Zec 12:12-14 the former word is used eleven times with powerful effect to indicate the separation of families and the isolation of wives through excessive grief in Jerusalem on account of the slain Messiah. The latter word signifies removal from ceremonial uncleanness (Le 15:19; 18:19; Eze 22:10). In Greek, kat' idian, "by themselves," of marked significance as expressing Christ's desire for privacy in prayer, alone or with His disciples; either in a desert (Mt 14:13); a mountain (Mt 14:23); or a high mountain, at the time of the transfiguration (Mt 17:1,19), thus suggestive of the secrecy of prayer and communion with God. Used with reference also to Christ's disclosures of His purpose and of the purport of His teaching in private to His disciples (Mt 20:17).
⇒See the definition of apart in the KJV Dictionary
Dwight M. Pratt