jock itch 
noun [mass noun] North American informal
A fungal infection of the groin area.Ringworm of the groin is called tinea cruris or jock itch....
- Also called tinea cruris, jock itch is closely related to other skin conditions with similar names.
- There are several common superficial fungal infections and jock itch is one of them.
Origin
1970s: jock from jockstrap.