Final answer:
Gliomas, particularly Glioblastoma Multiforme (GBM), are the most common primary brain tumors in adults, originating from glial cells.
Step-by-step explanation:
The question pertains to the identification of the most common primary cerebral neoplasm in adults. In the context of adult cancers, gliomas are the most common primary brain tumors in adults. These tumors arise from the glial cells in the brain. Glioblastoma Multiforme (GBM) is the most aggressive type of glioma and is highly malignant. It is important to note, that while this kind of information often comes up in medical training, for more detailed information regarding incidence and treatment, one should refer to medical texts and peer-reviewed articles.