is (uncountable) the state of being subadditive.

(of a function) such that the image of a sum is at most the sum of the images of the summands.

is that superadditive is (mathematics|of a function) such that the image of a sum is at least the sum of the images of the summands while subadditive is (of a function) such that the image of a sum is at most the sum of the images of the summands.

## As a noun summand

is something which is added or summed; for example in 1+2=3'' the summands are ''1'' and ''2'' which form the sum, ''3 .

(of a function) such that the image of a sum is at most the sum of the images of the summands.

## As a noun sum

is noise (sound or signal generated by random fluctuations).

(of a function) such that the image of a sum is at most the sum of the images of the summands.

#### Image vs Subadditive - What's the difference?

is that image is figurative (of sense of term or discourse) while subadditive is (of a function) such that the image of a sum is at most the sum of the images of the summands.

is .