S1 · ACPI S1 power state in computing · S1 , an administrative position within military units. · S1 , a line on the Berlin S-Bahn · S1 Invicta · In human anatomy it can refer to either: * First sacral vertebra of the vertebral column * In the brain, the primary somatosensory cortex · Nikon Coolpix S1 digital camera · First year in the Scottish education system · Comet Ikeya-Seki, C/1965 S1 · A safety phrase, meaning "keep locked up"; see List of S-phrases. · S1 MP3 Players · S1 Scout Car, an armoured car built in Australia during the Second World War · S1, Carex elata sedge-swamp, one of the swamp and tall-herb fen communities of the British National Vegetation Classification · a microprocessor-core, see S1 Core · S1 refers to the "lub" heart sound · S1, an innovative duplex locomo