The word "气宇轩昂" is formed by combining two two-character compounds: "气宇", which refers to a person's demeanor or bearing, derived from "气" (spirit) and "宇" (appearance), and "轩昂", meaning lofty or elevated, from "轩" (high) and "昂" (raised). The four characters together create a compound idiom where each part reinforces the concept of a noble and majestic outward presence.