'adagissimo' originates from Italian, specifically the word 'adagissimo', where 'adagio' meant 'slow' and the suffix '-issimo' intensifies the meaning to 'very slow'.

'adagissimo' has remained largely unchanged from its Italian origins, maintaining its use in musical contexts to denote a very slow tempo.

Initially, it meant 'very slow' in a musical context, and this meaning has remained consistent in modern usage.