The word **充气** is a modern Chinese compound noun (and verb) formed by combining two characters: **充** (*chōng*), meaning "to fill, to charge, to suffice," and **气** (*qì*), meaning "air, gas, vapor." It follows a verb-object grammatical structure where the first character denotes the action (*充* - to fill) and the second character is the object of that action (*气* - air/gas). Thus, the term literally means "to fill with air/gas," and by extension refers to something that is inflatable or the act of inflation itself, as in an **充气城堡** (*chōngqì chéngbǎo*, inflatable castle) or **给气球充气** (*gěi qìqiú chōngqì*, to inflate a balloon).