What does expeller mean?
An expeller is, at its core, something that forces out. The word can describe a person who expels another from a place or institution, but in contemporary English it survives chiefly as a technical term for a mechanical press used to extract oil from seeds, nuts, and other oily materials. In an expeller press, a rotating screw compresses the raw material against a restrictive cage until oil is squeezed out through small openings — a process celebrated on food labels as 'expeller-pressed,' which tells consumers the oil was obtained by physical pressure rather than chemical solvents like hexane. The term derives ultimately from the Latin pellere, 'to drive,' combined with ex-, 'out,' so its meaning has remained remarkably stable since it entered English. Though rarely encountered outside industrial, culinary, or formal contexts, expeller is a precise and useful word wherever the act of driving out — whether of people, substances, or oils — needs a name.
nounA person or thing that expels; especially a mechanical device that forces something out, most commonly a press that extracts oil from seeds or nuts by crushing them under intense pressure.
- A mechanical device, typically a screw press, that extracts oil from seeds or nuts by applying intense pressure.
- A person or agent that expels or forces someone out of a place, organization, or country.
"The mill's expeller pressed the sunflower seeds into oil without the use of chemical solvents."
"The coconut oil is expeller-pressed, retaining its natural flavor and aroma."
"As the school's chief disciplinarian, she was known as a relentless expeller of repeat offenders."
Standard plural; used mainly when referring to multiple presses in industrial contexts.
"The plant runs three expellers around the clock during harvest season."
That bottle labeled 'expeller-pressed' olive oil? It's naming the machine — a steel screw that crushes seeds so hard the oil literally squeezes out, no chemicals required.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of expeller
Expeller comes from the verb 'expel,' formed from the Latin ex- ('out') plus pellere ('to drive'), giving the sense 'to drive out.' The Latin compound expellere passed into English as 'expel' in the late medieval period, and the agent noun 'expeller' was formed later by adding the English suffix -er. It shares this root with a broad family of words built on pellere, including propel, repel, dispel, and expulsion.
Related word forms
How expeller is actually used
In modern usage, 'expeller' appears overwhelmingly in technical and commercial contexts relating to oil extraction, where 'expeller-pressed' signals an oil produced mechanically rather than with chemical solvents. Its older sense referring to a person who expels someone is now comparatively rare and somewhat formal.
Easily confused with expeller
An impeller is a rotating device that draws fluid inward to move it, whereas an expeller is a device that forces material outward, such as a screw press for extracting oil.