1. not yet payable

- an undue loan

2. not appropriate or proper (or even legal) in the circumstances

- undue influence

- I didn't want to show undue excitement

- accused of using undue force

3. lacking justification or authorization

- desire for undue private profit

Similar word(s): unreasonable, unjustified, unwarranted

4. beyond normal limits

- his dress stops just short of undue elegance

Similar word(s): immoderate, excessive, inordinate, unreasonable

Sentences with undue as an adjective:

- To individuals who despise killings in any form, death penalty is undue punishment.