a grin like a Cheshire cat

a very wide smile

Usage notes: The Cheshire cat is a character in Lewis Carroll's book Alice in Wonderland and is famous for its big smile.

I just presumed he'd got the job because he walked in here with a grin like a Cheshire cat.

Name	Pronounced	Usage
Kaloyan	-	Bulgarian
Armani	[a:'ma:ni]
Laelius	-	Ancient Roman
Macarius	-	Late Greek (Latinized)
Ned	NED	English
Glauco	GLOW-ko (Italian, Spanish)	Italian, Spanish, Portuguese