The name was invented by a Latin poet during the time of Jesus. He wrote the Odes to Cynthia, some of the earliest known love poetry. This poet wrote in the style of the Greeks and the name was originally Kynthia, meaning "from Mount Kynthus" a mountain on the island of Delos. Apollo was from Delos and he was the god of poetry. Cynthia was not the woman in the poems, she was the muse. So, in the style of the Greeks, her name is invoked at the beginning of each poem.
Cynthia is the muse for love poetry.
You are my Cynthia, my inspiration.