bolometer
noun
bo·lom·e·ter bō-ˈlä-mə-tər 
: a very sensitive thermometer whose electrical resistance varies with temperature and which is used in the detection and measurement of feeble thermal radiation and is especially adapted to the study of infrared spectra
bolometric
ˌbō-lə-ˈme-trik
adjective bolometrically
ˌbō-lə-ˈme-tri-k(ə-)lē
adverb 
Word History
Etymology
Greek bolē stroke, beam of light (from ballein to throw) + English -o- + -meter — more at devil
First Known Use
1878, in the meaning defined above
Medical Definition
bolometer
noun
bo·lom·e·ter bō-ˈläm-ət-ər
: a very sensitive thermometer used in the detection and measurement of feeble thermal radiation and especially adapted to the study of infrared spectra