低于 (dīyú, below) — use 零下 specifically for temperatures below zero, while 低于 can refer to any lower measurement.

Imagine a thermometer showing a big '0' with a downward arrow pointing to a snowy landscape. The '零' (líng) looks like a round zero, and '下' (xià) means 'below', so together they remind you of temperatures dropping below freezing.

Be cautious not to confuse 零下 with 零 (zero) alone. It's often used in weather contexts, so it's more common in formal settings like weather forecasts. Remember to pair it with temperature measurements, such as '零下10度' (10 degrees below zero).

While 零下 is not an HSK word, it connects to HSK Level 3 vocabulary related to weather and temperature. Focus on understanding how this term fits into practical conversations about climate and weather conditions.

In China, winter temperatures can often drop below zero in northern regions, making 零下 a common term in daily discussions about the cold season and the need for appropriate clothing.

Learners often mistakenly use 零下 with other contexts not related to temperature, such as '零下的价格' (below zero price), which is incorrect. Stick to temperature references to avoid confusion.