Ah (interjection)

1. Used to express pleasure, realization, or agreement.
2. Used to express hesitation or uncertainty.

Origin:

Late 16th century: representing a natural vocalization.

Examples:

1. Ah, that feels so good.
2. Ah, I see what you mean now.
3. Ah, I've been waiting for this moment.
4. Ah, I'm not sure what to say.
5. Ah, I'm not sure if I can make it to the meeting.