Definitions:

1. "in fact; truly." It is used to emphasize or confirm something that has been stated or suggested before. adverb
   • He is very good at math, indeed. (used to give extra emphasis to the degree of someone's ability)
   • I think it will rain later today, indeed. (used to express strong belief in the truth of what has been mentioned)
   • She did finish first in the race, indeed. (used to emphasize agreement with what has just been said)
   • they said the car would break down and indeed it did
2. (used as an interjection) an expression of surprise or skepticism or irony etc. adverb
   • Surprised to see such clear skies after days of rain? I exclaimed, "What a lovely morning indeed!" as I stepped outside.
   • Why, thank you for noticing my new haircut!" I replied with a smile, adding, "Indeed, I do feel more stylish now.

Synonyms:

• Absolutely
• Actually
• Admittedly
• As a matter of fact
• Certainly
• Definitely
• Honestly
• In reality
• In truth
• No doubt
• Of course
• Positively
• Really
• so
• Sure enough
• To be sure
• To tell you the truth
• True
• Truly
• Undoubtedly
• Verily