From Greek through Latin cactus, the plant name, used as a rare modern nature name.
Cactus comes from the Greek word kaktos, which passed through Latin as the name of a spiny plant. As a given name, it is extremely rare and belongs to the broad modern category of nature names that are chosen for image and symbolism rather than long convention. It immediately suggests dryness, resilience, and a landscape that survives by adaptation.
That gives Cactus an unusual personality among plant names. Where many nature names feel soft or floral, Cactus is sharp, desert-bright, and a little defiant. It can sound humorous to some ears and strikingly original to others, but it is never bland.
In naming, that kind of directness can be part of the charm: the name is memorable because it is so visual. Cactus feels like a name with edges, in the best literal sense.