Similarly, you cannot 'unstir' the sugar from a cup of coffee once it has been dissolved, and you never see a pile of ash in the fireplace 'unburn' to become a log of wood again.
Source: wiktionary
Unburn
Synonyms for "unburn"
Ranked by relevance and common usage.
Sample sentences
2 total sentences available.
In your class last year we learned that increase in entropy is why matches burn but never unburn, why cans rust but never unrust, and why engines are never perfectly efficient.
Source: wiktionary