Interjection

1. Indication of amazement or surprise or enthusiasm.

   Aah! That's amazing!

2. Indication of joyful pleasure.
   • 1834 — Edgar Allan Poe, The Assignation

     Yet I remember—aah! how should I forget?

3. Indication of sympathy.
4. Indication of mouth being opened wide.

   Dentists would always instruct, say aah!

5. To express understanding.

   Aah. Now I understand.

Noun

1. Expression of amazement or surprise or enthusiasm.
2. Expression of joy and/or pleasure.
3. The exclamation aah.

Verb

1. To express amazement or surprise or enthusiasm, especially by the interjection aah.

   Everyone who came by oohed and aahed over her new appearance.

2. To express joy or pleasure, especially by the interjection aah.
3. To say or exclaim aah.

Usage notes

• Usually the verb is intransitive. The object of feelings usually is indicated by the prepositions over or at; sometimes it occurs as a direct object, especially in passive constructions.
• Very often the word is used together with some other verb derived from an interjection. The most common combination is to ooh and aah. Perhaps it should be regarded as a separate lexical item.
• The word belongs to the informal style.