The word 足够 is formed by combining two characters that both independently convey the idea of sufficiency or adequacy. The first character, 足, originally picturing a foot, carries the core meaning of "sufficient" or "full". The second character, 够, itself composed of 句 (sentence/sufficient) and 多 (many), means "enough" or "to reach a point". They are placed side-by-side in a parallel structure, where each reinforces and echoes the meaning of the other, creating a single, emphatic concept of "enough" or "adequate" through this semantic duplication.