|Easton's Bible Dictionary|
A companion and fellow-labourer of Paul during his first imprisonment at Rome (Philemon 1:24; Colossians 4:14). It appears, however, that the love of the world afterwards mastered him, and he deserted the apostle (2 Timothy 4:10).
Int. Standard Bible Encyclopedia
de'-mas (Demas, "popular"): According to Colossians 4:14 2 Timothy 4:10; Philemon 1:24, one who was for a time a "fellow-worker" with Paul at Rome (Col, Philem), but at last, "having loved this present world," forsook the apostle and betook himself to Thessalonica (2 Tim). No other particulars are given concerning him. See APOSTASY; DEMETRIUS.
Demas (3 Occurrences)
Colossians 4:14 Luke, the beloved physician, and Demas greet you. (WEB KJV WEY ASV BBE DBY WBS YLT NAS RSV NIV)
2 Timothy 4:10 for Demas left me, having loved this present world, and went to Thessalonica; Crescens to Galatia, and Titus to Dalmatia. (WEB KJV WEY ASV BBE DBY WBS YLT NAS RSV NIV)
Philemon 1:24 as do Mark, Aristarchus, Demas, and Luke, my fellow workers. (WEB KJV WEY ASV BBE DBY WBS YLT NAS RSV NIV)