Butyric Acid
An off flavor in beer that causes cheesy, rancid, putrid, and baby vomit-type flavors at concentrations above its beer flavor threshold.
Retronasal Aroma
Orthonasal and retronasal olfaction send messages to your brain to tell it what you are eating or drinking. While you can taste five basic tastes (sweet, sour, bitter, salty, and umami), you can distinguish thousands of volatile chemical compounds.