Real Dictionary

excuse me
(used as a polite expression, as when addressing a stranger, when interrupting or disagreeing with someone, or to request repetition of what has just been said)
an expression used to catch someone's attention or to apologize for an interruption, disagreement, or social indiscretion
convention: You say ' Excuse me' when you want to politely get someone's attention, especially when you are about to ask them a question.
convention: You say 'Excuse me?' to show that you want someone to repeat what they have just said.
convention: You say excuse me to apologize when you have bumped into someone, or when you need to move past someone in a crowd.
convention: You say excuse me to apologize when you have done something slightly embarrassing or impolite, such as burping, hiccupping, or sneezing.
convention: You use excuse me or a phrase such as if you'll excuse me as a polite way of indicating that you are about to leave or that you are about to stop talking to someone.
convention: You use excuse me to apologize to someone when you have disturbed or interrupted them.
convention: You use excuse me, but to indicate that you are about to disagree with someone.
noun: a dance in which a person may take another's partner