The story
- Proto-Indo-European*speḱ-
- Proto-Indo-European*spéḱyeti
- Proto-Italic*spekjō
- Latinspeciō
- Latinspectrum
- Englishspectrum
- Englishspectro-
- Proto-Indo-European*bʰeh₂-
- Proto-Indo-European*bʰéh₂os
- Proto-Hellenic*pʰáwos
- Ancient Greekφᾰ́ος (phắos)
- Ancient Greekφῶς (phôs)
- Ancient Greekφωτο- (phōto-)
- Englishphoto-
- Proto-Indo-European*ǵónu
- Proto-Hellenic*gónu
- Proto-Hellenic*gonwía
- Ancient Greekγωνίᾱ (gōníā)
- Englishgonio-
- Proto-Indo-European*med-
- Proto-Indo-European*meh₁-
- Ancient Greekμέτρον (métron)
- Englishgoniometer
- Englishphotogoniometer
- English todayspectrophotogoniometer
From spectro- + photogoniometer.
Etymology from Wiktionary, CC BY-SA 4.0.