Separate - Vine's Expository Dictionary of New Testament Words
Separate[ A-1,Verb,G873, aphorizo ]
to mark off by bounds" (apo, "from," horizo, "to determine;" horos, "a limit"), "to separate," is used of "
(a) the Divine action in setting men apart for the work of the gospel, Romans 1:1; Galatians 1:15;
(b) the Divine judgment upon men, Matthew 13:49; Matthew 25:32;
(c) the separation of Christians from unbelievers, Acts 19:9; 2 Corinthians 6:17;
(d) the separation of believers by unbelievers, Luke 6:22;
(e) the withdrawal of Christians from their brethren, Galatians 2:12. In
(c) is described what the Christian must do, in
(d) what he must be prepared to suffer, and in
(e) what he must avoid."* [* From Notes on Galatians, by Hogg and Vine, p. 83.]
[ A-2,Verb,G5563, chorizo ]
"to put asunder, separate," is translated "to separate" in Romans 8:35, Romans 8:39; in the Middle Voice, "to separate oneself, depart" (See DEPART); in the Passive Voice in Hebrews 7:26, RV, "separated" (AV, "separate"), the verb here relates to the resurrection of Christ, not, as AV indicates, to the fact of His holiness in the days of His flesh; the list is progressive in this respect that the first three qualities apply to His sinlessness, the next to His resurrection, the last to His ascension. See PUT, No. 14.
[ A-3,Verb,G592, apodiorizo ]
"to mark off" (apo, "from," dia, "asunder," horizo, "to limit"), hence denotes metaphorically to make "separations," Jude 1:19, RV (AV, "separate themselves"), of persons who make divisions (in contrast with Jude 1:20); there is no pronoun in the original representing "themselves."
[ B-1,Preposition,G5565, choris ]
"apart from, without" (cp. aneu, "without," a rarer word than this), is translated "separate from" in Ephesians 2:12 (AV, "without"). See APART, BESIDE, WITHOUT.