- Helio is defined as something related to light, the sun, or sunlight.
An example of helio is Helios, the Greek sun god.
helio- definition by Webster's New World
Origin: Classical Latin ; from Classical Greek hēlio- ; from hēlios, sun
helio- definition by American Heritage Dictionary
Origin: Greek hēlio-, from hēlios, sun; see sāwel- in Indo-European roots.