'Cyanophyta' originates from New Latin, specifically the word 'Cyanophyta', where the prefix 'cyano-' meant 'dark blue' (from Greek 'kyanos') and 'phyta' meant 'plants' (from Greek 'phyton').

'Cyanophyta' formed in botanical/New Latin from Greek elements 'kyanos' and 'phyton'; it was used in 19th- and 20th-century classifications for blue-green algae and later applied to the group now usually called 'cyanobacteria'.

Initially, it meant 'blue-green plants' (i.e., algal organisms perceived as plants), but over time it evolved into its current usage referring to a group of photosynthetic bacteria (cyanobacteria).