IPA: /sɛfəˈlɒmətri/
KK: /sɛfəˈlɑːmətri/
The scientific study and measurement of the dimensions and proportions of the head.
Cephalometry is often used in orthodontics to assess the relationship between the teeth and the jaw.
Cephalometry is formed from "cephalo-" (from Greek "kephalē", meaning head) and "-metry" (from Greek "metron", meaning measure). The word refers to the measurement of the head, particularly in relation to its size and shape.
Think of 'head' ('cephalo-') being 'measured' ('-metry') — that's what cephalometry means.