To renege is to go back on a promise, to make a denial, or revoke something. It is pronounced many different ways. The first syllable may have the long or short e sound. And the (nege) syllable can be /nehg/, /nahg/, or /nig/.
A person who reneges is a reneger.
It is also used sometimes in board or card games when a player has broken the rules. In the game of euchre, you play cards by suit. If you play a card later, but should have played it earlier in the game, you reneged on the promise that you had no more of that suit.
Rescind is a verb that means to officially terminate something, like a law or contract. It may also mean to repeal or cancel. A person who rescinds is a rescinder. An uncommon noun form is rescindment.
The difference between the two is mostly that rescind is more formal and renege is looser. Therefore, rescind is found more often in written texts.
Examples
Sunday’s election is expected to be won by the radical leftist party Syriza, whose leader Alexis Tsipras, has threatened to renege on at least half of the billions of dollars in debt that Greece owes its creditors, the European Union and the International Monetary Fund. [The Telegraph]
The Houthis had virtually held Hadi prisoner at his home this week after accusing him of reneging on a power-sharing agreement they signed with the main political parties after seizing the capital. [DW]
Aldermen in Starkville voted to override a mayor’s veto of their decision to rescind two resolutions passed in 2014 that made it clear that the city is intolerant of discrimination against the LGBT community. [The Clarion Ledger]
The appeal was filed in December 2013, and it seeks to overturn a ruling by Judge Allan J. Goodman in Los Angeles County Superior Court, rescinding the building permits issued for the former site of the Great Indoors adjacent to the Empire Center, in which Walmart planned to open a store. [Burbank Leader]