Definition
A liquid product obtained by heating a mixture until selected components vaporize, then cooling those vapors back into liquid form. In aviation fuels and lubricants, distillates are the fractions separated from crude oil during refining, each captured at a specific temperature range to yield products such as aviation gasoline, jet fuel (kerosene), and lubricating oils.
Plain English
A liquid that has been purified or separated by boiling it off as vapor and then turning it back into liquid. Crude oil is heated, and different useful liquids -- like avgas and jet fuel -- come out at different temperatures.
Context Anchor
Seen in aviation fuel, turbine engine, and aircraft maintenance discussions.
Derivation
From the Latin distillare, meaning 'to drip down.' The original idea was that vapor cooled and dripped back into liquid form -- which is exactly what happens in a refinery still.
Why Pilots Care
Aviation fuels and oils are specific distillates with tightly controlled properties. Knowing that avgas and jet fuel are different distillate fractions helps explain why they cannot be substituted for each other and why fuel contamination matters.
Analogy
It is like boiling water and catching the steam as liquid again, except a refinery does it with crude oil to separate useful fuel products.
Intuition Check
Distillate does not mean “distilled water” or a drinking-water product. Here it means a petroleum liquid separated by heating and cooling.
Example Sentence 1
Jet fuel is a middle distillate of crude oil, captured at a higher temperature range than aviation gasoline.
Example Sentence 2
Technicians drained the tanks to remove any contaminated distillate before refilling with fresh product.