Boyd’s Bible Dictionary:

(city of Philip). City in Macedonia, founded by Philip II., 12 miles from the port of Neapolis. Through Paul’s preaching souls were saved, resulting in a vigorous church there (Acts 16; 20:1-6).

Concise Bible Dictionary:

City in the east of Macedonia. It was founded by Philip the father of Alexander the Great, from whom it derived its name. It was the first European city visited by Paul. His preaching was blessed to the conversion of Lydia and others. On his casting out a spirit of divination from the young woman who followed him, a tumult was raised, and Paul and Silas were scourged and cast into prison; but this happily led to the conversion of the jailor and his household (Acts 16:12-40). Paul visited the place for a short time afterward (Acts 20:6). To the church gathered there the Epistle to the Philippians was written (Phil. 1:1; 1 Thess. 2:2). Extensive ruins are all that are left of the ancient city, now called Kavalla. It was the chief city, not of all Macedonia, but of that part of it.

Strong’s Dictionary of Greek Words:

plural of 5376; Philippi, a place in Macedonia
KJV Usage:

Jackson’s Dictionary of Scripture Proper Names:

same as Philip

Potts’ Bible Proper Names:

Lover of horses; warlike:―a place in Macedonia, Acts 16:12. {Amator equorum}