预兆 (yù zhào) is a noun meaning 'omen' or 'forewarning'—a sign that something, often significant or momentous, is about to happen. The first character 预 (yù) means 'in advance' or 'beforehand', conveying anticipation; the second character 兆 (zhào) originally referred to cracks appearing in heated turtle shells during ancient divination, later broadening to mean 'portent' or 'sign'. Together, they emphasize a visible or perceptible signal preceding an event—often with connotations of inevitability or gravity.

This word appears frequently in literary, historical, and superstitious contexts: natural phenomena (e.g., unusual animal behavior), human actions (e.g., sudden political shifts), or even personal experiences (e.g., dreams or physical sensations). It carries a formal or slightly solemn tone and is rarely used in casual speech. While neutral in theory, 预兆 often implies something consequential—positive or negative—and is commonly paired with adjectives like 不祥 (bù xiáng, 'inauspicious') or 吉祥 (jí xiáng, 'auspicious').