UVB Definition
 yo͝ovēbē 
    noun
  
 Ultraviolet light with a shorter wavelength than UVA and thus closer in size to X-rays.
 Webster's New World 
Origin of UVB
- u(ltra)v(iolet) B (the letter B being used to designate the second of the categories based on wavelength in which ultraviolet radiation is classified) - From American Heritage Dictionary of the English Language, 5th Edition