ˌhēlēˈägrəfē noun
( -es )
1.
[French héliographie, from hélio- heli- (I) + -graphie -graphy]
: an early photographic process producing a photoengraving on a metal plate coated with an asphalt preparation ; broadly : photography
2.
[ heli- (I) + -graphy ]
: the system, art, or practice of signaling with a heliograph