Describe blockchain as one kind of distributed verifiable data structure.

[Mindonaut]

If we break blockchain unto its constituting elements, we will find that it is a data structure that makes things like unforgettability (immutability) and authentication verifiable.
By adding cryptographic primitives such as signing and hashing to a computer language's basic data types, we may create a wide variety of these data structures that go beyond blockchains.
We may have verifiably immutable linked list of transaction blocks, but we might also create verifiably immutable linked graphs, whose data structure elements may be signed by their respective creators, allowing for verification and access control, and go beyond replication into general distribution, enabling distributed ACID transactions across a network of VMs.

[dukejones]

1. This is what blockchain does: verifiable in this way, ...
2. Here is how we can do each of those things, or any subset.