Candour: the quality of being open and honest
Rancour: a feeling of deep and bitter anger and ill-will

These words do not originate in the same language, and really, the similarity likely ends with the last three letters. Nor, sadly for me, does rancour become the adjective ‘rancid’, like ‘candour’ becomes ‘candid’.

Still, the meaning behind the word rancour evokes a sense that if that feeling were to have an odour, it would most certainly be of something that had gone off, and no one had bothered to dispose of it. That sticky, pungent smell that often coats the bottom of the cupboard where the oils are stored that is very difficult to remove. The idea that emotions can be as volatile as delicate oils is a poignant one. And, that exposing them to the air requires that they must be used up and not allowed to linger. 

Stale tears smell like walnut oil that should have been in the salad mix last summer. Not something you want on your face.