Bond (4886) (sundesmos sundesmos from sundéo = join together in turn from sun = with, speaks of an intimate union + deo = bind) describes that which binds together. Sundesmos describes that which holds something together and was used for example to describe the fastenings that hold the various ships together. TDNT writes that sundesmos (syndesmos)... is the “middle thing” that serves as a “link,” “joint,” “loop,” or “bond,” and in grammar “conjunction.” Special meanings are “chain,” “cable,” or “halter.” In Plato the term takes on special significance as the mediation or union that overcomes cosmic dualism. Figuratively for Aristotle it refers to “children” as the bond between father and mother. In rhetoric it may be a “connecting word,” and physiologically it is the “joint” or “muscle.” (Kittel, G., Friedrich, G., & Bromiley, G. W. Theological Dictionary of the New Testament. Eerdmans) Sundesmos was used in Greek to describe a tendon or ligament of the bones by which the members of the human body are united together. It denotes that which keeps something together. It's the "tie which binds together". In secular Greek writings sundesmos was used to describe "good men" who form the bond that keeps the state (government) together! Moulton and Milligan quote Aristeas who writes "the great doorway and the fastenings (sundesmos) which held it to the door-posts". In Ephesians of course sundesmos is used figuratively to picture the binding together in the sense of the spiritual forces that unite believers. It is peace which brings both groups into a unified relationship and peace which will maintain them in that relationship of unity. In Colossians 3:14 we see that it is love which is the bond that unites all the virtues Paul had just listed (see notes Colossians 3:12; 3:13) Sundesmos is used more often in the Septuagint (LXX) (1Ki 14:24; 2Ki 11:14; 12:20; Job 41:15; Isa 58:6, 9; Jer 11:9; Da 5:6, 12). Below are the only other NT uses of sundesmos (note the use in Colossians 3 which parallels Eph 4:3)... (Acts 8:23) (Peter addressing Simon the sorcerer who was trying to obtain the gift of God with money declared) "For I see that you are in the gall of bitterness and in the bondage of iniquity." (Comment: Here sundesmos is used in a negative sense to describe the unspiritual forces that enslave people and so bring them into bondage or put them in a fetter and thus describes that which causes one to be under control, in this case the control of iniquity. Unrighteousness was like a fetter [chain or shackle for the feet, restraining from motion] binding and controlling Simon!) (Colossians 2:19 - see note) and not holding fast to the Head from Whom the entire body , being supplied and held together by the joints and ligaments (sundesmos), grows with a growth which is from God (Colossians 3:14 - see note) And beyond all these things put on love, which is the perfect bond (sundesmos) of unity. (Comment: This passage parallels Ephesians 4:3, but here Paul substitutes love for peace.