Frolic is a playful word with a happy history. It traces back to the Dutch word vroolijk (merry), which in turn evolved from a Middle Dutch combination of vro (happy) and the adjectival suffix -lijc (-ly).
A normal PSA level is considered to be 4.0 ng/mL (nanograms per milliliter of blood). 1  For men in their 50s or younger, a PSA level should be below 2.5 in most cases.  Older men often have slightly higher PSA levels than younger men.
Prostate Specific Antigen, (PSA) , is an enzyme found in the blood produced exclusively by prostate cells. Small amounts, levels between 0-2.5 ng/ml, of PSA in blood are normal.