photogoniometer

Etymology tree
Proto-Indo-European *bʰeh₂-
Proto-Indo-European *bʰéh₂os
Proto-Hellenic *pʰáwos
Ancient Greek φᾰ́ος (phắos)
Ancient Greek φῶς (phôs)
Ancient Greek φωτο- (phōto-)der.
English photo-
Proto-Indo-European *ǵónu
Proto-Hellenic *gónu
Ancient Greek γόνῠ (gónŭ)der.
Ancient Greek γωνίᾱ (gōníā)der.
English gonio-
Proto-Indo-European *meh₁-
Proto-Indo-European *-tḗr
Proto-Indo-European *-trom
Proto-Hellenic *-tron
Ancient Greek -τρον (-tron)
Ancient Greek μέτρον (métron)der.
English -meter
English goniometer
English photogoniometer
From photo- + goniometer.