Consistence vs Undefined - What's the difference?

As a noun consistence

is (archaic) the physical quality which is given by the degree of firmness, solidity, density, and viscosity; consistency.

lacking a definition or value.

(archaic) The physical quality which is given by the degree of firmness, solidity, density, and viscosity; consistency.

* Arbuthnot

Let the expressed juices be boiled into the consistence of a sirup.

The staying together, or remaining in close relation, of non-physical things.

Her performance has lacked consistence over the last year.

This composer's musical work is of extraordinary consistence .

(obsolete) Standing still; quiescence; state of rest.

(obsolete) The condition of standing or adhering together, or being fixed in union, as the parts of a body; existence; firmness; coherence; solidity.

* Francis Bacon

Water, being divided, maketh many circles, till it restore itself to the natural consistence .

* Jeremy Taylor

We are as water, weak, and of no consistence .

(obsolete) That which stands together as a united whole; a combination.

* Milton

The church of God, as meaning whole consistence of orders and members.

(wikipedia undefined) (-)

Lacking a definition or value.

(mathematics, computing) That does not have a meaning and is thus not assigned an interpretation.

The result of division by zero is undefined .

* defined