What's Nonnegotiable?

There is no scope for alteration of the terms and conditions especially the price factor, quantitative or qualitative elements at the option of intended seeker.

Irreconcilable 

Irrevocable 

Non-transferable

 Non-bargain-able

Nonnegotiable

 All these words give the same meanings  

To negotiate is to hold a discussion in order to achieve a common ground. Hence, something non-negotiable cannot be changed even after discussion. For example, a non-negotiable price is a price that is fixed and cannot be bargained.

1.Not able to be bought, sold, exchanged, or transferred. This term can be applied to documents or other instruments. See also non-negotiable instrument.

2.Not open to negotiation. "The terms of this contract are absolutely non-negotiable; the company will not budge." 

1. not open to discussion or modification.

 Not able to be bought, sold,irreconcilable,  exchanged, or transferred. It cannot be changed even after discussion.

Colleagues excellent answers

Private answer Mr. Vinod Jntley

Thanks for the invite

The terms were non-negotiable and that meant that no one could argue with what was being done and what was expected.

Something that is fixed and not possible to change through discussions. Non-negotiable generally refers to something that cannot be bought, sold, exchanged or transferred.

Something that is not open to discussion or modification.

I'm Agree With Mr. Vinod Jetley  In His Answer

Non negotiable is defined as a contract is correct in terms of commercial, technical & duration.