Here are some options depending on the situation:
General:
* Meeting: This is a general term for coming together with someone.
* Interaction: This refers to a reciprocal exchange or communication.
* Confrontation: This implies a tense or hostile meeting.
Specific:
* Clash: This suggests a conflict or disagreement.
* Run-in: This implies a brief and unexpected encounter.
* Brush-up: This suggests a brief and casual encounter.
* Encounter: This can be used as a noun itself to refer to a specific event.
* Experience: This refers to a lived event, including encounters.
You can also use phrases like "a chance meeting," "a brief encounter," or "a memorable experience" to convey the specific type of encounter you are talking about.
Ultimately, the best noun to use will depend on the specific context of your sentence.