What is a credit score? gives consumer reporting industry and federal government definitions for the term credit score.
Experian: 15 definitions on 7 websites. Takes the prize for the most shelf space and elegant variation.
Equifax: Among others, gives the FICO score definition. Discord with TransUnion over what period FICO predicts.
TransUnion: Typographical error in FAQ.
FICO (the artist formerly known as Fair, Isaac and Fair Isaac), U.S. Treasury, HUD, FTC, FDIC and FCIC finish the set.