What is defined as an unfinished wooden box or a non-metal receptacle for encasing human remains?

The term that accurately describes an unfinished wooden box or a non-metal receptacle for encasing human remains is "alternative container." This term specifically refers to a simpler, often less expensive option that does not conform to the traditional casket style, which can include various materials and constructions that are designed to hold the human body for burial or cremation. Alternative containers are significant in the funeral industry as they provide families with more economical and environmentally friendly choices.

In contrast, the other options either refer to broader concepts or specific items with distinct definitions. "Funeral service" pertains to the overall process and rituals associated with honoring and dispositioning the deceased, while "casket" typically implies a more elaborately designed container, often made of wood or metal. "Embalming vessel" refers specifically to the container used during the embalming process to hold fluids and may not necessarily be associated with the final resting place of the remains. Thus, "alternative container" is the most suitable and precise answer for the definition provided in the question.