The word Entropy comes from Physics and it means:

1. a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.

2. The other meaning is:
   lack of order or predictability; gradual decline into disorder.
   "a marketplace where entropy reigns supreme"

Synonyms: deterioration, degeneration, crumbling, decline, degradation, decomposition, breaking down, collapse...

Entropy in my photo series:

When you look at the photos you see a "system" that's is degrading, it's gradualy declining into disorder, into decay, it's decomposing. Now the degradation you see on my photos is somewhat predictable though.

I hope the answer satisfies you :)