variants: or sub-zero
Definition of subzero
1 : registering less than zero on some scale (especially the Fahrenheit scale) subzero temperatures
2 : characterized by or suitable for subzero temperatures subzero winters sub-zero snow boots Here the altitude was almost a mile and a half above sea level and there was already hard frost in the mornings. With the first storm, the mornings would be subzero.— Tony Hillerman
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