Strong formal apology

To convey deep regret, often in serious or formal situations such as significant mistakes, offending someone, or handling customer complaints.

When a person makes a major error that caused inconvenience or offense; when addressing senior clients or authority figures.

Professional settings (business meetings, emails), official correspondence, polite interactions with customers or superiors.

I'm terribly sorry

I'm terribly sorry

terribly → awfully, dreadfully, extremely; can also use 'very' for less formal registers.

• "I'm terribly sorry for the inconvenience."

• I sincerely apologize
• Please accept my apologies

Using this phrase in minor or everyday mistakes may sound exaggerated; mismatching register with overly informal situations.

I apologize (formal), I'm very sorry (neutral tone).

'Terribly' as an intensifier can be unfamiliar to some speakers; British English commonly uses 'terribly' whereas American English might prefer 'very'.

• Formal apologies: I sincerely apologize
• My sincerest apologies
• Do forgive me.

The expression signals genuine remorse and is intended for serious offenses, leaving no doubt of the speaker's contrition.

Reassures the offended party that the speaker takes responsibility seriously and intends to rectify the situation.

must apologize

In American English, 'I'm very sorry' is more common than 'I'm terribly sorry'.

I'm sorry → I'm terribly sorry → I cannot apologize enough (more emphatic).