The word "一心" is a classical Chinese compound formed by combining the numeral "一" (yī), meaning "one" or "whole", with the noun "心" (xīn), meaning "heart" or "mind". It functions as an idiomatic expression where the literal "one heart" is used metaphorically to convey the abstract concept of undivided attention, singular purpose, or complete devotion. The formation follows a common modifier-noun structure in Chinese, where "一" specifies the state of the "心", resulting in a meaning greater than the sum of its parts: "wholeheartedly" or "of one mind".