In common speech, your definition of "disposable income" is perfectly acceptable. https://www.merriam-webster.com/dictionary/disposable%20income https://www.me

In common speech, your definition of "disposable income" is perfectly acceptable. https://www.merriam-webster.com/dictionary/disposable%20income https://www.merriam-webster.com/dictionary/disposable%20inco... https://dictionary.cambridge.org/dictionary/english/disposable-income https://dictionary.cambridge.org/dictionary/english/disposab... Note that the Oxford Dictionary uses GP's definition, probably to distinguish themselves from Cambridge :) https://en.oxforddictionaries.com/definition/disposable_income https://en.oxforddictionaries.com/definition/disposable_inco... It's probably a case of a word used incorrectly, but so often that ends up assuming a different meaning.