'daisy' originates from Old English, specifically the word 'dæges ēage', where 'dæges' meant 'day's' and 'ēage' meant 'eye', referring to the flower opening in the morning.

'dæges ēage' changed from Old English to Middle English as 'dayeseye', and eventually became the modern English word 'daisy'.

Initially, it meant 'day's eye', referring to the flower that opens in the day, but over time it became the name for the specific flower and also gained the informal meaning of something excellent.