In every form of it was sternly condemned by the Mosaic law (Leviticus 21:9; 19:29; Deuteronomy 22:20,21,23-29; 23:18; Exodus 22:16). (See ADULTERY .)
But this word is more frequently used in a symbolical than in its ordinary sense. It frequently means a forsaking of God or a following after idols (Isaiah 1:2; Jeremiah 2:20; Ezek. 16; Hosea 1:2; 2:1-5; Jeremiah 3:8,9).
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 'Fornication'". "Easton's Bible Dictionary".