residual is waste, that is, what is left over and what is qualified as the rest of something.
This term can be applied to refer to the residue of certain physical matter, as well as the idea of something immaterial that presents itself as surplus.
In the tax legal field, for example, the definition of residual competence (also known as remnant), consists of the power given to the Union to establish, through laws complementary, the collection of new taxes, provided that they are not cumulative to those previously described in the Constitution.
These new taxes are now known as "residual taxes", due to the character of the competence that created them.
Among the main synonyms of residual, stand out: residual, remainder and surplus.
Residual value
This is a concept applied in the area of accounting, used to define the expected value of a given product after the end of its useful life and based on devaluation rates.
Typically, most equipment and products maintain a residual value between 10% and 20% of the initial purchase value.
See also the meaning of Income tax.