The story
- Proto-Indo-European*speḱ-
- Proto-Indo-European*spéḱyeti
- Proto-Italic*spekjō
- Latinspeciō
- Latinspectrum
- Englishspectrum
- Englishspectro-
- 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
- English todayspectrogoniometer
From spectro- + goniometer.
Etymology from Wiktionary, CC BY-SA 4.0.