In the Old Testament denotes (1) a particular part of the body of man and animals (Genesis 2:21; 41:2; Psalms 102:5, marg.); (2) the whole body (Psalms 16:9); (3) all living things having flesh, and particularly humanity as a whole (Genesis 6:12,13); (4) mutability and weakness (2 Chronicles 32:8; Compare Isaiah 31:3; Psalms 78:39). As suggesting the idea of softness it is used in the expression "heart of flesh" (Ezekiel 11:19). The expression "my flesh and bone" (Judges 9:2; Isaiah 58:7) denotes relationship.
In the New Testament, besides these it is also used to denote the sinful element of human nature as opposed to the "Spirit" (Romans 6:19; Matthew 16:17). Being "in the flesh" means being unrenewed (Romans 7:5; 8:8,9), and to live "according to the flesh" is to live and act sinfully (Romans 8:4,5,7,12).
This word also denotes the human nature of Christ (John 1:14, "The Word was made flesh." Compare also 1 Timothy 3:16; Romans 1:3).
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Flesh'". "Easton's Bible Dictionary".