Definitions

1. adjective

having a temperature below zero degrees Celsius or zero degrees Fahrenheit

“The subzero temperatures made it difficult to venture outdoors.”

2. noun

a temperature below zero degrees Celsius or zero degrees Fahrenheit

“The forecast warned of subzero temperatures for the entire week.”

3. adverb

below zero degrees Celsius or zero degrees Fahrenheit

“The thermometer read subzero, and the pilot took evasive action.”