Strong’s Lexicon
Definition - servant, slave, bondservant
Word Origin - Derived from the root verb δέω (deo), meaning “to bind.”
Usage - The term “doulos” in the New Testament is used to describe a person who is in a position of servitude or subjection. It can refer to a literal slave, someone who is legally owned by another and whose entire livelihood and purpose are determined by their master. However, it is also used metaphorically to describe a person who is devoted to another to the disregard of their own interests, often used to describe followers of Christ who are committed to serving God and His purposes.
HELPS Word-studies
1401 doúlos (a masculine noun of uncertain derivation) – properly, someone who belongs to another; a bond-slave, without any ownership rights of their own. Ironically, 1401 /doúlos (“bond-slave”) is used with the highest dignity in the NT – namely, of believers who willingly live under Christ’s authority as His devoted followers.