From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( n.) That which is held as an opinion; a tenet; a doctrine.

(2): ( n.) A formally stated and authoritatively settled doctrine; a definite, established, and authoritative tenet.

(3): ( n.) A doctrinal notion asserted without regard to evidence or truth; an arbitrary dictum.

International Standard Bible Encyclopedia [2]

dog´ma ( δόγμα , dógma , from δοκέω , dokéō , "that which seems," "an opinion," particularly the opinion of a philosopher):

In the decadent period of Greek philosophy, the opinion, or ipse dixit , of the master of a philosophical school came to be quoted as authoritative truth; also, the opinion of a sovereign imposed as law upon his subjects: a decree or ordinance of the civil authority. The word never appears in English Versions of the Bible, although it is used 5 times in the Greek New Testament, but with the one exception of  Acts 16:4 , in a sense widely different from that which ecclesiastical usage has given to it from the 2nd century downward. "Dogma" is used in the New Testament, (1) of Roman laws: "a decree (Greek dogma ) from Caesar Augustus" ( Luke 2:1 ); "the decrees of Caesar" ( Acts 17:7 ) = the whole body of Roman law; (2) of ordinances of religious law: "the law of commandments contained in ordinances" ( Ephesians 2:15 ); "the bond written in ordinances" ( Colossians 2:14 ) = the Mosaic ordinances as expressing the moral law which condemned the sinner, and whose enmity Christ abolished by His death. It is a significant revelation of the spirit of Greek theology that all the Greek commentators understood by ordinances in these two places, the gospel as a body of dogmas which had removed the commandment or bond that was against us (see Lightfoot, Colossians , at the place); (3) of the decrees of the Council of Jerusalem ( Acts 15:20 ), which Paul and his companions delivered to the Gentile churches ( Acts 16:4 ). Here we have one element that entered into the later ecclesiastical meaning of the word. These dogmas were decisions on religious matters, imposed by a more or less authoritative council of the church as a condition of admission to its membership.

There is however one important difference. These decrees relate to moral and ceremonial matters, but from the 2nd century downward, dogma means especially a theological doctrine. In Greek theology "doctrine" and "dogma" meant the same thing. Each had its origin in the opinion of some great teacher; each rested upon revelation and claimed its authority; each meant an exposition of a particular truth of the gospel, and of the whole Christian truth, which the church adopted as the only right exposition. Each word might be used for the teaching of a philosopher, or of a heretic, although for the latter, "heresy" became the regular term. On the one side stood the doctrines or dogmas of the majority or the "Catholic" church, and on the other side, those of the heretics. So long as the "Catholic" ideal of orthodoxy and uniformity of belief held the field, there was no room for the distinction now made between "doctrine," as a scientific and systematic expression of the truth of the Christian religion, and "dogma," as those truths "authoritatively ratified as expressing the belief of the church." This distinction could only arise when men began to think that various expressions of Christian truth could coexist in the church, and is therefore quite modern and even recent. Dogma in this sense denotes the ancient conception of theology as an authoritative system of orthodoxy, and doctrine, the modern conception, outside the dogmatic churches, where theology is regarded as a scientific exposition of truth.

Harnack, History of Dogma , I, chapter i; Drummond, Studies in Christian Doctrine , 1-7.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [3]

(Gr. Δόγμα ), a doctrine received as an article of faith. I. In the Scriptures the Greek word Δόγμα has nowhere the meaning of doctrine. In  Ephesians 2:15, and  Colossians 2:14, it denotes Jewish ordinances. In other passages ( Luke 2:1;  Acts 16:1;  Acts 17:7) it designates the decrees of Roman emperors. II. This term is used by some of the earliest writers of the Christian Church, both Greek and Latin, to designate a doctrine of the Christian Church, or the whole of the Christian doctrines. Thus, by Ignatius, in the epistle to the Magnesians (chapter 13), the Christian doctrines are called Δόγματα Τοῦ Κυρίου Καὶ Τῶν Ἀποστόλων , and by Origen (in Matth. tom. 12, § 23), Δόγματα Θεοῦ . In his work against Celsus ( Contra Celsum , 3, c. 39) he calls the whole of the Christian doctrines Τὸ Δόγμα , and the apostles Διδάσκαλοι Τοῦ Δόγματος . The ecclesiastical writers of the 2d and 3d centuries also applied it to the tenets of philosophical schools. But the meaning Christian doctrine came to be the common use of the word in the theological and ecclesiastical language of the Greek and Latin writers, and from the Latin it has passed into most of the modern languages, especially those of Roman Catholic countries. In English, the word Dogma, in this theological sense, is only of late coming much in use, but Doctrine has generally been used instead of it.