A redeem script is the script used to unlock bitcoin sent to a P2SH address. A P2SH transaction locks bitcoin to the hash of a redeem script.
A reorganization, often shortened to reorg, occurs when a block is removed from the blockchain because a longer chain has been created. This is a damaging event to the Bitcoin network and especially to the miner(s) who mined the removed block(s) as they lose the block reward from that block.
A Replace-by-Fee transaction allows the sender of a transaction to raise the fee after submitting the transaction to the network in order to speed up the confirmation time. This can only be done when the transaction is still in the mempool.
The Round Amounts Heuristic, otherwise known as the Change Output Heuristic is used in chain analysis to track ownership of bitcoin across transactions.