Yeah, it’s a generic term meaning the quorum decreases over time. So say your base case is 3-of-5 multisig. You could make an address which allows 3-of-5 at any time, then allows 2-of-5 after say a year, and then 1-of-5 after another year.

That way, in a catastrophe, like losing 4 keys, you can still recover the funds if you just wait.

You can also have an initial unspendable period. So say you make an address that is completely unspendable for 1 month, then 3-of-5 for a year, etc. Your attacker can’t force you to give them coins until the first month is up. Literally impossible to comply with the wrench attack.

By staggering the durations, you can have a rotating vault. So say you make 4 addresses, fully locked at 3-month, 6-month, 9-month and 12-month intervals. Each quarter, one fourth of your coins become available to spend. When that happens, move what you need to your hot wallet, then roll the rest into a fresh 12-month address.

This dovetails into inheritance planning. Your decaying multisig can have additional rules that make the coins spendable by your heirs—that is, different keys from your regular quorum, but only after the decay period is completed.

All of this is made possible by the Bitcoin script protocol already, and Taproot adds privacy. I’m trying to find out what existing open source wallets (if any) provide UX for these cases.