Sunday

Sunday is an English day name whose literal meaning is “day of the sun.” The word belongs to the historical practice of naming days after celestial bodies and deities. It also has a Christian association as a day of worship, but that religious use is separate from its original solar wording.

Sunny is a natural nickname, while the full name retains the calendar connection. A child does not need to be born on a Sunday for the name to be meaningful: families may choose it for a memory, a religious association, or its sound. The familiar word gives the name an immediate explanation, without implying that its bearer will always have a cheerful temperament.