accelerometer
From Longman Dictionary of Contemporary Englishaccelerometerac‧cel‧e‧rom‧e‧ter /əkˌseləˈrɒmɪtə $ -ˈrɑːmɪtər/ noun [countable] a piece of technology in a mobile phone or small computer that makes sure images and writing are shown in the correct way for the direction of the screen