Daisy is the English name of the common meadow flower, derived from the Old English dæges ēage — "day's eye" — referring to the way the flower opens its white petals at dawn and closes them at dusk, like an eye watching the day.
Daisy was popular in the late Victorian era alongside other flower names (Rose, Lily, Violet, Iris), faded for most of the twentieth century, and has returned strongly in the 2010s. Today it sits in the U.S. top 130. In the United Kingdom it has been in the top 30 for two decades.
Daisy does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Daisy reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.