Definitions:

1. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
2. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
3. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
4. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
5. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
6. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
7. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
8. happening unexpectedly adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
9. without warning adverb
   • All of a sudden, a loud bang interrupted our quiet afternoon.
10. without warning adverb
    • We were surprised when all of a sudden, she started singing.
11. without warning adverb
    • He fell asleep on the couch and all of a sudden, he was snoring loudly.
12. without warning adverb
    • All of a sudden, the lights went out and the room was plunged into darkness.
13. without warning adverb
    • I was feeling fine, and then all of a sudden, I started feeling dizzy and sick.
14. without warning adverb
    • All of a sudden, the car in front of us stopped and we had to slam on the brakes.
15. without warning adverb
    • She was talking normally, and then all of a sudden, she burst into tears.
16. without warning adverb
    • All of a sudden, a gust of wind blew through the room, scattering papers everywhere.

Synonyms:

• all at once
• from nowhere
• out of nothing
• out of thin air
• suddenly