Noun:
* Surprise (the feeling itself)
* Surprise (an unexpected event)
* Surprise (an unexpected gift)
* Surprise (a feeling of astonishment)
* Surprised (a state of being surprised)
Verb:
* Surprise (to cause someone to feel surprise)
* Surprised (past tense of "surprise")
* Surprising (present participle of "surprise")
* Surprisedly (adverb, meaning "in a surprised manner")
Adjective:
* Surprised (feeling surprise)
* Surprising (causing surprise)
* Unexpected (not anticipated)
* Astonishing (causing great surprise)
* Startling (causing a sudden surprise)
Other:
* Surprisal (the act or state of being surprised)
The specific word form you choose will depend on the context of your sentence. For example, you might use "surprised" to describe someone's reaction to an unexpected event, or "surprising" to describe the event itself.