counteroffer

Definition from Nolo’s Plain-English Law Dictionary

The rejection of an offer to enter into a contract that simultaneously makes a different offer, changing the terms of the original offer in some way. For example, if a buyer offers $5000 for a used car, and the seller replies that he wants $5500, the seller has rejected the buyer's offer of $5000 and has made a counteroffer to sell at $5500. The legal significance of a counteroffer is that it completely voids the original offer.

Definition provided by Nolo’s Plain-English Law Dictionary.