The most significant cultural and linguistic point about 词 (cí) is its distinction from 字 (zì), a character. This distinction is a fundamental conceptual shift for learners from alphabetic languages. A 字 is a logogram, a symbol representing a concept or syllable (e.g., 人, rén - person). A 词 is the functional vocabulary unit used in speech and writing (e.g., 人们, rénmen - people).
Comparison to a Western Concept: Think of the difference between a “morpheme” and a “word” in English. A morpheme is the smallest unit of meaning (like “un-”, “port”, “-able”). You combine them to make a word (“unportable”). In a simplified sense, a 字 (zì) is like a morpheme—it has meaning, but you often need to combine it with other 字 to form a complete 词 (cí), or “word,” that you would use in a sentence.
This concept highlights the modular nature of Chinese. Understanding the meaning of individual characters allows you to intelligently guess the meaning of new words you encounter. For example, knowing 电 (diàn, electricity) and 脑 (nǎo, brain) helps you understand 电脑 (diànnǎo, electric brain), the 词 for “computer.”