Abnormal growth of cells in the nervous system without evidence of malignant characteristics. Unlike other organ systems, tumors in the central nervous system can have benign histological characteristics but still have life threatening effects due to their location within the neuraxis (e.g., brainstem gliomas). The disease is Monarch Disease Ontology identifier MONDO_0000648 (nervous system benign neoplasm). Also known as: benign neoplasm of nervous system, benign neoplasm of the nervous system, benign nervous system neoplasm, benign nervous system tumor, benign nervous system tumour, benign tumor of nervous system, benign tumor of the nervous system, benign tumour of nervous system.