flat
Mes plus plates excuses.
My sincerest apologies.
— Le Patient anglais (1996)
Il allait marcher sur nos plates bandes.
He was going to step on our toes.
— Drive (2011)
Je te dois de plates excuses.
I owe you a profuse apology.
Je te présente de plates excuses.
I sincerely apologize to you.
Je vous dois de plates excuses.
I owe you a sincere apology.