What is the definition or description of: enlarged testicular veins?

Varicocele. This occurs in 15% of the adult population and is not typically visible until after puberty. It is almost always on the left side, and if seen on the right additional evaluation needs to be performed. It is more common in men with infertility and if treated can reverse the infertility.
Varicocele. Some men have a plexus of thickened / distended veins usually along the left spermatic cord. If it's new, it warns of possible obstruction of a renal vein perhaps by tumor; if it's a nuisance, it can be removed. Good luck.