只身 (zhǐ shēn) literally combines 只 (zhǐ), meaning 'only' or 'solely', and 身 (shēn), meaning 'body' or 'person'. Together, they convey the idea of being physically alone—without companions, family, or support—emphasizing solitude in action or movement. It’s not merely about being physically by oneself, but about undertaking something independently, often with a sense of determination or vulnerability.

This term is commonly used in formal or literary contexts—such as news reports, essays, or narratives—to describe someone traveling, migrating, studying, or starting anew without others. It carries a subtle nuance of courage or hardship; for example, 只身赴美 implies not just 'going to America alone', but doing so with resolve amid uncertainty. It rarely appears in casual speech, where simpler terms like 独自 or 一个人 are preferred.