From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( n.) A manumitted slave; a freedman; also, the son of a freedman.

(2): ( n.) Dissolute; licentious; profligate; loose in morals; as, libertine principles or manners.

(3): ( n.) Free from restraint; uncontrolled.

(4): ( n.) A defamatory name for a freethinker.

(5): ( n.) One free from restraint; one who acts according to his impulses and desires; now, specifically, one who gives rein to lust; a rake; a debauchee.

(6): ( n.) One of a sect of Anabaptists, in the fifteenth and early part of the sixteenth century, who rejected many of the customs and decencies of life, and advocated a community of goods and of women.

Charles Buck Theological Dictionary [2]

One who acts without restraint, and pays no regard to the precepts of religion.

Holman Bible Dictionary [3]

 Acts 6:9

Easton's Bible Dictionary [4]

 Acts 6:9

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [5]

( Λιβερτῖνος , for the Latin Libertinus, a Freed-Man) occurs but once in the N.T., "Certain of the synagogue, which is called (the synagogue) of the Libertaies, and Cyrenians, and Alexandrians," etc. ( Acts 6:9). There has been much diversity in the interpretation of this word. The structure of the passage leaves it doubtful how many synagogues are implied in it. Some (Calvin, Beza, Bengel) have taken it as if there were but one synagogue, including men from all the different cities that are named. Winer (N.T. Gramm. page 179), on grammatical grounds, takes the repetition of the article as indicating a fresh group, and finds accordingly two synagogues, one including Libertines, Cyrenians, Alexandrians; the other those of Cilicia and Asia. Meyer (Comment. ad loc.) thinks it unlikely that out of 480 synagogues at Jerusalem (the number given by rabbinic writers, Megill. 73:4; Ketub. 105:1) there should have been one, or even two only, for natives of cities and districts in which the Jewish population was so numerous (in Cyrene one fourth, in Alexandria two fifths of the whole [Josephus, Ant. 14:7, 2; 14:10, 1; 19:5, 2; War, 2:13, 7;  Revelation 2:4]), and on that ground assigns a separate synagogue to each of the proper names. Of the name itself there have been several explanations.

1. The other names being local, this also has been referred to a town called Libertum, in the proconsular province of Africa. This, it is said, would explain the close juxtaposition with Cyrene. Suidas recognizes Λιβερτῖνοι as Ὄνομα Ἔθνους , and in the Council of Carthage in 411 (Mansi, 4:265- 274, quoted in Wiltsch, Handbuch der Kirchlich. Geogr. § 96) we find an Episcopus Libertinemsis (Simon. Onornasticon N. Test. page 99). Against this-hypothesis it has been urged (1) that the existence of a town Libertum, in the 1st century, is not established; and (2) that if it existed, it can hardly have been important enough either to have a synagogue at Jerusalem for the Jews belonging to it, or to take precedence of Cyrene and Alexandria in a synagogue common to the three.

2. Conjectural readings have been proposed, especially Libyans, either in the form Λιβοστίνων ((Ecumen., Beza, Clericus,Valckenaer), or Λιβύων (Schultness, De Char. Sp. S. page 162, in Meyer, ad loc.); inasmuch as Libertini here occurs among the names of nations, and Josephus (Ant. 12:1, and Apion. 2:4) has told us that many Jews were removed by Ptolemy, and placed in the cities of Libya. The difficulty is thus removed, but every rule of textual criticism is against the reception of a reading unsupported by a single MS. or version.

3. Taking the word in its received meaning as = Freedmen, Lightfoot finds in it a description of natives of Palestine, who, having fallen into slavery, had been manumitted by Jewish masters (Exc. On  Acts 6:9 ). In this case, however, it is hardly likely that a body of men so circumstanced would have received a Roman name.

4. Grotius and Vitringa explain the word as describing Italian freedmen who had become converts to Judaism. In this case, however, the word "proselytes" would most probably have been used; and it is at least unlikely that a body of converts would have had a synagogue to themselves, or that proselytes from Italy would have been united with Jews from Cyrene and Alexandria.

5. The earliest explanation of the word (Chrysostom) is also that which has been adopted by the most recent authorities. The Libertini are Jews who, having been taken prisoners by Pompey and other Roman generals in the Syrian wars, had been reduced to slavery, and had afterwards been emancipated, and returned, permanently or for a time, to the country of their fathers. Of the existence of a large body of Jews in this position at Rome we have abundant evidence. Under Tiberius, the Senatus-Consultum for the suppression of Egyptian and Jewish mysteries led to the banishment of 4000 "libertini generis" to Sardinia, under the pretense of military or police duty, but really in the hope that the malaria of the island might be fatal to them. Others were to leave Italy unless they abandoned their religion (Tacitus, Anal. 2:85; comp. Sueton. Tiber. c. 36). Josephus (Ant. 18:3, 5), narrating the same fact, speaks of the 4000 who were sent to Sardinia as Jews, and thus identifies them with the "libertinum genus" of Tacitus. Philo (Legat. ad Caiunm, page 1014, C) in like manner says that the greater part of the Jews of Rome were in the position of freedmen ( Ἀπελευθερωθέντες ), and had been allowed by Augustus to settle in the Trans-Tiberine part of the city, and to follow their own religious customs unmolested (comp. Horace, Sat. 1:4, 143; 1:9, 70). The expulsion from Rome took place A.D. 19; and it is an ingenious conjecture of Mr. Humphreys (Comm. On Acts, ad loc.) that those who were thus banished from Italy may have found their way to Jerusalem, and that, as having suffered for the sake of their religion, they were likely to be foremost in the opposition to a teacher like Stephen, whom they looked on as impugning the sacredness of all that they most revered. The synagogue in question had doubtless been built at the expense of these manumitted Jews, and was occupied by them. Libertini is thus to be regarded as a word of Roman origin, and to be explained with reference to Roman customs. Among the Romans this term was employed to denote those who had once been slaves, but had been set at liberty, or the children of such persons (see Adam's Romans Ant. pages 34, 41 sq.; Smith's Dict. of Class. Antiq. s.v. Ingenui, Libertus). This view is further confirmed by the fact that the word Συναγωγῆς does not occur in the middle of the national names, but stands first, and is followed by Τῆς Λεγομένης , whence it clearly appears that Λιβερτῖνοι is at least not the name of a country or region. On this subject, see further in Bloomfield, Kuinll, Wetstein, etc., on  Acts 6:9; and comp. D. Gerdes, De Synog. Libertinoraum (Gron. 1736); J.F. Scherer, De Synag. Libertin. (Argent. 1754); Briam, De Libertinis (Hafn. 1698); Cademann, De schola Libertinorum (Lips. 1704); L Ö sner, Obs. in N. Test. page 180; Deyling, Observ. 2:437 sq.; K. D Ö ring, Ep. qua synagogam Libert. scholamn Latinamz fuisse conjicit (Laube, 1755). (See Dispersed); (See Slavery).