Deca-dick means impotence, sex loss and other sexual dysfunction symptoms, it occurs during cycles while taking something like Deca-durabolin without Testosterone or any other high Androgenic Steroid
it's mainly occurs not because the inhibition of natural Testosterone production only but due to low Blood Testosterone level during the cycle
while taking something like Deca-durabolin which is classified as 19-Nor-Progesterone (A Progestin) it will inhibit natural Testosterone roduction "Gonadotrophins and HPTA" while as being classified as 19-Nor-Testosterone and it lacks the 19position therefor it has a little Androgenic effects and will cause little peaking in blood Testosterone level
therefor inhibited Testosterone production+low blood Testosterone level = absolutely loss of sex drive or as known as Deca-dick