The phrase exogenous semiotic entropy is from a recent "peer reviewed" "paper". It looks like something that came out of a buzzphrase generator which was having a bad hair day. The phrase is, of course, complete nonsense. As it stands.
If someone had taken the trouble to error-check their paper, they would have found - along with all the other errors - that the phrase should have read "exogenous biosemiotic entropy".
Within the intended context, these definitions apply:
exogenous - adj. A term in biology meaning: derived or developed from outside the body; originating externally.
biosemiotic - adj. Of or pertaining to signs and signaling mechanisms in biological organisms.
- from the Greek bios meaning "life" and semeion meaning "sign".
entropy - noun. A process of degradation or running down or a trend to disorder.
Biosemiotic entropy: a process of degradation of a biological signaling function.
Exogenous biosemiotic entropy: a process of degradation of a biological signaling function due to an influence originating from outside the organism.
Here is a real scientific example of exogenous biosemiotic entropy: proof of a chemical causing damage to DNA.
And to conclude, here is an image of a low-technology exogenous biosemiotic entropy application apparatus.