Mortify - Vine's Expository Dictionary of New Testament Words
Mortify
[ 1,,G2289, thanatoo ]to put to death" (from thanatos, "death," akin to thnetos, "mortal," See above), is translated "mortify" in Romans 8:13 (Amer. RV, "put to death"); in Romans 7:4, "ye were made dead" (Passive Voice), betokens the act of God on the believer, through the death of Christ; here in Romans 8:13 it is the act of the believer himself, as being responsible to answer to God's act, and to put to death "the deeds of the body." See DEATH, C, No. 1.
[ 2,,G3499, nekroo ]
"to make dead" (from nekros, See DEAD, A), is used figuratively in Colossians 3:5 and translated "mortify" (Amer. RV, "put to death"). See DEAD, B, No. 1.