Milk that has spoiled is an example of something that would be described as rancid.
The house was deserted, with a rancid half-eaten meal still on the dinner table.
Origin of rancid
- Latin rancidus from rancēre to stink, be rotten
From American Heritage Dictionary of the English Language, 5th Edition
- From Latin rancidus (“stinking, rank, rancid, offensive"), from ranceÅ (“to stink") (sense in Middle Latin), from whence also English rancor, in Latin used only in present participle rancens (“stinking").