The word "骨子" is formed by combining the character "骨" (gǔ), meaning "bone", which conveys the core semantic idea of structure or foundation, with the character "子" (zi), a nominal suffix that often forms nouns indicating a derivative or smaller aspect. Together, they create a compound noun where "骨" provides the meaning related to an inner framework or essence, and "子" functions as a grammatical marker that solidifies the term as a noun referring to the inherent or deep-seated part of something, such as in the phrase "骨子里" meaning "at the core" or "in one's bones".