Uncle Block
A valid block that was not included in the canonical chain due to a competing block at the same height; may still receive partial rewards.
On account-based chains like Ethereum (pre-merge), when two miners found blocks nearly simultaneously, one became canonical while the other was an "uncle" (ommer). Uncles help improve security and decentralization by rewarding near-miss blocks.
"A miner whose block lost the race still received an uncle reward when another miner referenced it, reducing variance in miner income."
Related Terms
Block
→A collection of transactions confirmed on the blockchain, each block building upon the previous one.
Chain Reorganization
→A network event where the active chain tip switches to a different branch with more accumulated work.
Confirmations
→The number of blocks added to the blockchain since a transaction was included.
All terms and definitions may update as the Cryptionary improves.
