sub-zero

[suhb-zeer-oh] /sʌbˈzɪər oʊ/
adjective
1.
indicating or recording lower than zero on some scale, especially on the Fahrenheit scale:
"a week of sub-zero temperatures."
2.
characterized by or appropriate for sub-zero temperatures:
"sub-zero climates; sub-zero clothing for the exploration."
Origin

Difficulty index for sub-zero

Few English speakers likely know this word

Tile value for sub

5
7
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Quotes with sub-zero