Helios

[hee-lee-os] /ˈhi liˌɒs/
noun
1.
the ancient Greek god of the sun, represented as driving a chariot across the heavens; identified by the Romans with Sol.

helio

[hee-lee-oh] /ˈhi liˌoʊ/
noun, plural helios. Informal.
1.
a heliogram.
2.
a heliograph.
Origin
by shortening
British Dictionary definitions for Helios

Helios

/ˈhiːlɪˌɒs/
noun
1.
(Greek myth) the god of the sun, who drove his chariot daily across the sky Roman counterpart Sol