There are several synonyms for the phrase "alter the terms of contract," including modify, change, amend, revise, adjust, and vary. These terms all convey the idea of making alterations or adjustments to an existing contractual agreement. Depending on the nature and extent of the changes, they may require the consent or approval of all parties involved in the contract, or they may be made unilaterally by one party. Regardless of the specific wording used to describe changes made to a contract, it is important to ensure that any modifications are clearly communicated and documented in writing in order to avoid confusion or disputes later on.