咫尺 (zhǐ chǐ) is a classical Chinese idiom meaning 'an extremely short distance'—so close that it feels almost touchable. Literally, 咫 (zhǐ) was an ancient unit of length equal to about 8 inches (roughly the width of a hand), and 尺 (chǐ) was another traditional unit, about 12 inches (the length of a foot). Together, they form a poetic, slightly literary expression emphasizing proximity—not just physical nearness, but also emotional or situational closeness, like being 'right there' yet somehow unreachable.

This term appears frequently in literature, poetry, and formal speech, often carrying a subtle tone of irony or wistfulness: two people may be 咫尺 apart yet emotionally distant, or a goal may seem 咫尺 away but remain unattainable. It’s rarely used in casual daily conversation, but learners will encounter it in news headlines, essays, and idiomatic expressions such as 咫尺天涯 (zhǐ chǐ tiān yá, 'a thumb-and-foot from the horizon'—i.e., near yet infinitely far).