Helio is defined as something related to light, the sun, or sunlight.
(prefix)An example of helio is Helios, the Greek sun god.
See helio- in Webster's New World College Dictionary
Origin: L < Gr hēlio- < hēlios, sun
See helio- in American Heritage Dictionary 4
or heli-
prefixOrigin:
Origin: Greek hēlio-
Origin: , from hēlios, sun; see sāwel- in Indo-European roots
.