The word "紧紧" is formed through the process of full reduplication, where the single-character adjective "紧" (meaning tight, close, or firm) is simply repeated. This doubling does not create a new core meaning but instead intensifies the original concept, emphasizing a state of being very tight, closely adhering, or firmly held. The formation is purely morphological, relying on the repetition of the identical character to amplify its inherent qualitative sense.