Merriam-Webster:
* 1: having or showing reason or sound judgment
* 2: being within the bounds of common sense
* 3: not excessive or extreme
Oxford English Dictionary:
* 1: having or showing reason or sound judgment; fair and sensible.
* 2: (of a price or charge) moderate or fair.
* 3: (of a quantity) moderate in amount.
* 4: (of a person) capable of reason or rational thought.
Cambridge Dictionary:
* 1: fair and sensible
* 2: not too much or too little; a reasonable amount
* 3: able to think and behave in a sensible way
These definitions all emphasize the core meaning of "reasonable" as something that is based on reason, logic, and sound judgment. It also often implies being fair, moderate, and not excessive in its application.