I. -raf, -rȧf noun
Etymology: International Scientific Vocabulary heli- (I) + -graph
1.
a. : photoengraving 2b
b. : photograph
c. : photoheliograph
2. : an apparatus for telegraphing by means of the sun's rays thrown from a mirror — compare heliotrope 3
II. verb
: to signal by means of a heliograph