"bloody"

[Vanessa]

The 'strength' or otherwise of 'bloody' really only depends on your 
perspective.

One of the things I really like about Ron is his occassional 'strong' 
language (especially where JKR refuses to tell us what word he's used 
and just says that Hermione objects to it...)

Bloody alone is probably no stronger than 'git', which Ron also uses 
a lot.  So-called 'religious' swear words are generally considered 
less 'strong' than sexual or faecal swear words; I'd've got away with 
bloody, or hell, or Oh my God!  at school, but not shit or f***.

Saying "that was bloody brilliant" to a teacher would probably get 
you a sharp look, and require an "Oops, sorry", but it wouldn't merit 
a punishment.

Bloody occassionaly gets turned into 'ruddy', which I believe Hagrid 
says quite a bit.