non-adjustable

adjective

capable of being adjusted: adjustable seat belts.
(of loans, mortgages, etc.) having a flexible rate, as one based on money market interest rates or on the rate of inflation or cost of living.
(especially of life insurance) having flexible premiums and coverage, based on the insuree’s current needs and ability to pay.

noun

any rate, expense, income, etc., that varies unpredictably: Luckily, his chief income is not made up of adjustables. Allow some money in your budget for the adjustables.

adj.1775, from adjust + -able. Related: Adjustably; adjustability.