Not exactly. Hardy means the plant can handle a cold climate or winter like day lilies or irises. They need that cold season. However, not all perennials are hardy like some gardenias, tropical hibiscus.

The term refers to cold tolerance, and a perennial that is hardy can survive lower temperatures than an annual that is hardy, which can survive a light frost. Sweet peas are hardy and planted outside long before you would put a zinnia out.