未知数

• Pinyin: wèi zhī shù
• Hanzi breakdown: 未 (not yet); 知 = 矢 + 口 (know, be aware of); 数 = 娄 + 攴 (number, count)

Meaning

Unknown quantity; variable in mathematics. Figuratively, something uncertain, unpredictable, or yet to be determined.

Originally a mathematical term for variables in equations (x, y). In everyday Chinese, used figuratively to describe uncertain outcomes, unpredictable people, or unresolved situations. Common in both formal writing and conversational speech.

Examples

1. 这次谈判的结果仍是一个未知数。 The outcome of these negotiations is still unknown.
2. 方程中有两个未知数，需要联立方程组求解。 The equation has two unknowns and needs to be solved using a system of equations.
3. 新政策实施后市场将如何反应，目前还是个未知数。 How the market will react after the new policy is implemented is still an open question.

Usage Guide

Context: academic, business, conversation

Tone: neutral

Do Say

• 他能否胜任这份工作，目前仍是个未知数，需要观察一段时间。(Whether he can handle this job remains an unknown quantity — we need to observe for a period of time.)
• 项目最终能带来多少收益，现在还是未知数，风险不可忽视。(How much revenue the project will ultimately generate is still uncertain, and the risks cannot be ignored.)

Don't Say

• 这件事有未知数个可能性 — use 多种 or 无数种 for 'many possibilities'; 未知数 is a noun meaning 'an unknown', not a quantifier

Origin & History

未知 (unknown, not yet known) + 数 (number, quantity)

Cultural Context

Generation: All ages

Social background: Universal