from an Aramaic word peras (found in Daniel 5:28 ), signifying "to separate," owing to a different manner of life from that of the general public. The "Pharisees" and Sadducees appear as distinct parties in the latter half of the 2nd cent. B.C., though they represent tendencies traceable much earlier in Jewish history, tendencies which became pronounced after the return from Babylon (537 B.C.). The immediate progenitors of the two parties were, respectively, the Hasideans and the Hellenizers; the latter, the antecedents of the Sadducees, aimed at removing Judaism from its narrowness and sharing in the advantages of Greek life and culture. The Hasidaeans, a transcription of the Hebrew chasidim, i.e., "pious ones," were a society of men zealous for religion, who acted under the guidance of the scribes, in opposition to the godless Hellenizing party; they scrupled to oppose the legitimate high priest even when he was on the Greek side. Thus the Hellenizers were a political sect, while the Hasidaens, whose fundamental principle was complete separation from non-Jewish elements, were the strictly legal party among the Jews, and were ultimately the more popular and influential party. In their zeal for the Law they almost deified it and their attitude became merely external, formal, and mechanical. They laid stress, not upon the righteousness of an action, but upon its formal correctness. Consequently their opposition to Christ was inevitable; His manner of life and teaching was essentially a condemnation of theirs; hence His denunciation of them, e.g., Matthew 6:2,5,16 ; 15:7 and chapter 23.
While the Jews continued to be divided into these two parties, the spread of the testimony of the Gospel must have produced what in the public eye seemed to be a new sect, and in the extensive development which took place at Antioch, Acts 11:19-26 , the name "Christians" seems to have become a popular term applied to the disciples as a sect, the primary cause, however, being their witness to Christ (see CALL , A, No. 11). The opposition of both "Pharisees" and Sadducees (still mutually antagonistic, Acts 23:6-10 ) against the new "sect" continued unabated during apostolic times.
Vines, W. E., M. A. Entry for 'Pharisees'. Vine's Expository Dictionary of NT Words. https://www.studylight.org/dictionaries/ved/p/pharisees.html. 1940.