The spelling of the word "Oncograph" can be explained using IPA phonetic transcription. The first syllable "Onco" is pronounced as /ˈɑŋ.koʊ/, with emphasis on the first syllable. The second syllable "graph" is pronounced as /ɡræf/, with the emphasis on the second syllable. Together, the word is pronounced as /ˈɑŋ.koʊ.ɡræf/. The word "Oncograph" is a combination of two words, "onco" meaning cancer and "graph" meaning writing or recording. Therefore, Oncograph refers to a device that records or measures cancerous growth in the body.
A recording oncometer, or the recording portion of an oncometer.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.