/ sʌb; NAmE / prefix
1.
(in nouns and adjectives) below; less than :
sub-zero temperatures
a subtropical (= almost tropical) climate
substandard
2.
(in nouns and adjectives) under :
subway
submarine
3.
(in verbs and nouns) a smaller part of sth :
subdivide
subset
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WORD ORIGIN
from Latin sub under, close to.