dialectology

Etymology tree
Proto-Indo-European *dwóh₁
Proto-Indo-European *dwísder.
Ancient Greek διά (diá)
Ancient Greek δῐᾰ- (dĭă-)
Proto-Indo-European *leǵ-der.
Proto-Indo-European *léǵ-e-ti
Proto-Hellenic *légō
Ancient Greek λέγω (légō)
Ancient Greek διαλέγομαι (dialégomai)
Proto-Indo-European *-tós
Proto-Hellenic *-tós
Ancient Greek -τος (-tos)
Ancient Greek δῐᾰ́λεκτος (dĭắlektos)bor.
Latin dialectoslbor.
Middle French dialectebor.
English dialect
Ancient Greek -ο- (-o-)der.
Latin -o-bor.
English -o-
Proto-Indo-European *leǵ-
Ancient Greek λόγος (lógos)
Proto-Indo-European *-h₂
Proto-Indo-European *-éh₂
Proto-Indo-European *-i-eh₂
Proto-Hellenic *-íā
Ancient Greek -ῐ́ᾱ (-ĭ́ā)
Ancient Greek -λογῐ́ᾱ (-logĭ́ā)bor.
Latin -logialbor.
French -logiebor.
English -logy
English dialectology
From dialect + -o- + -logy.