The idiom "似曾相识" (sì céng xiāng shí) is formed through a classical literary structure where each character contributes to a layered meaning: "似" (sì) means "to seem" or "resemble," "曾" (céng) means "once" or "ever," and "相识" (xiāng shí) means "to be acquainted with" or "to recognize." Combined, they create the poetic meaning of "to seem as if one has met or recognized something/someone before," perfectly capturing the psychological sensation of déjà vu. It functions as a fixed, inseparable phrase whose meaning is greater than the sum of its parts, typical of Chinese chengyu (成语).