Just for the record (little pun): several rap & hard rock band names included the word -- Def Jam, Def Jef, and (better known) Def Leppard (Guinness Encyclopaedia of Popular Music -- the best I know).
...also, i think the name Def Leppard came before the word Def meant cool etc.
they just liked the name Deaf Leopard and altered the spelling.
could be wrong tho, i haven't checked.
I'm sure you're right, trevor --- was only browsing around in those 6 enormous volumes I once invested in -- of course nowadays you'd find far more on the subject by googling.