The word 俯首称臣 is formed by sequentially combining two verb-object constructions: 俯首, meaning "to bow one's head", and 称臣, meaning "to declare oneself a subject". The characters 俯 (bow) and 首 (head) depict a physical act of submission, while 称 (declare) and 臣 (subject) express the subsequent verbal acknowledgment of subordination, together creating a compound phrase that literally represents the actions of bowing and pledging allegiance.