Final answer:
The term that refers to a unique sign as a personal identifier for someone in the Deaf community is Signature Sign.
Step-by-step explanation:
The term that refers to a unique sign that acts as a personal identifier for an individual who has participated in the Deaf community for a long time is Signature Sign. In Deaf culture, a signature sign is a personalized sign name that is earned by an individual based on their involvement and contributions to the Deaf community. It is a mark of recognition and respect within the community.