S5

S5 or S-5 may refer to:

==Science== Pentasulfur (S5), an allotrope of sulfur S5, the symmetric group on five elements S5: Keep contents under ... (appropriate liquid to be specified by the manufacturer), a safety phrase in chemistry Sacral spinal nerve 5, a spinal nerve of the sacral segment S5, the fifth sacral vertebra of the vertebral column, in human anatomy