Ephelis: A form of freckle. A flat red or light-brown spot on the skin that typically appears during the sunny months and fades in the winter. They are most often found in people with light complexions and in some families, they are an hereditary (genetic) trait. The regular use of sunscreen during times of sun exposure helps to suppress the appearance of the ephelis-type freckle.
Ephelis is Greek for freckle. The plural is ephelides.