Definition of pyro-photography in US English:

pyro-photography

noun

historical
  • A photographic process in which the image is caught on a glass surface coated or dusted with a fusible substance that hardens on exposure to light, heat being subsequently applied to fix the image.

Origin

Mid 19th century; earliest use found in Photography Journal. From pyro- + photography.

Pronunciation

pyro-photography

/ˌpʌɪrəʊfəˈtɒɡrəfi/