Synonyms for Rancid (same or very similar meaning)
WordNet sense 1 (showing deterioration from age):
stale
WordNet sense 2 (smelling of fermentation or staleness):
sour
WordNet sense 3 (having an unpleasant smell):
malodorous, stinky, malodourous, ill-smelling, unpeasant-smelling
From the ODE community, based on WordNet
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