'auf' originates from Proto-Germanic, specifically the reconstructed form '*upp' (or '*upą'), where '*up-' meant 'up' or 'upwards'.

'auf' changed from Old High German 'uf' (also Middle High German 'uf') and, through regular sound developments including the High German consonant shift and vowel changes, eventually became the modern German word 'auf'. It is cognate with English 'up' and Dutch 'op'.

Initially it meant 'up' or 'upwards' (direction). Over time it developed the related senses of 'on' (position), 'onto' (motion to a surface), the colloquial 'open' (state), and grammaticalized into a separable verb prefix indicating upward motion or opening.