What do Alyssa Milano's tattoos mean?

Ouroboros. Based on my research it is an Ouroboros, which depicts a dragon or snake swallowing it's tail and forming a circle. According to Alyssa Milano it stands for rebirth, which she got soon...

It is on her right shoulder blade and has a width of about 2 inches and the height is a little over 2.5 inches.

she has 3, on her neck, on her back, on her wrist.

The Buddhist symbol for Om which is used in many religious chants and symbolizes the essence of the universe

eight.