I've looked up in the dictionary and didn't find a noun form of the word disjoint. What is the word if I want to mean the fact that 2 things are disjointed?
Disjointedness is the noun form of disjoint, and means the quality of being disjoint. If you're asking for a noun that applies to objects that are themselves disjoint, I think you're out of luck, and disjoint things is as close as you can get.
Disjointed is the adjective used to describe something that is lacking a coherent sequence or connection.
The OED gives the noun disjoint as an obsolete word meaning A disjointed or out-of-joint condition; a position of perplexity or difficulty; a dilemma, ‘fix’. The adjective disjointed is given with these three definitions:
- Separated joint from joint; disjoined, separated; disconnected.
- Consisting of separated or ill-connected parts; disconnected.
- Of words or a discourse: Without proper connection or sequence; disconnected; incoherent.
As an American English speaker, I would understand if you told me, "these two figures are non-intersecting." You could also tell me they are not connected or independent of one another. To say they are disjointed implies to me that for each figure. The angles are 'akimbo' or poorly connected/structured. To say that anything is 'disjoint' sounds very odd to me, but it sounds like this fits among mathematicians.