siphon
SY-fuhn
/ˈsaɪfən/
A tube used to convey liquid upwards from a reservoir and then down to a lower level, operating by atmospheric pressure; to draw off liquid using this method.
Implies drawing liquid out using pressure differentials rather than mechanical pumping.
The story behind the word. The ancient Greeks used the word 'siphon' to describe the hollow reeds or metal tubes they used to taste wine directly from large storage casks. Alexandrian engineers like Hero of Alexandria later studied the physics of these tubes, formalizing the siphon as a scientific tool.
Word relationships
- draw off: 'Draw off' is a general term for removing liquid, while 'siphon' specifies the physical pressure method.
- drain: 'Drain' relies purely on gravity through an open bottom hole, whereas 'siphon' pulls liquid up and over an obstacle first.
Commonly confused with
- pump: A pump uses mechanical energy to move fluid, while a siphon relies on gravity and atmospheric pressure once the flow is initiated.
Collocations
- siphon tube
- siphon effect
- siphon off
- create a siphon
Idioms & expressions
- siphon off (funds)
Example sentences
- "The rapid rush of water into the toilet bowl creates a siphon that pulls waste down the drain." Explaining how a toilet empties.
- "He used a flexible plastic hose to siphon the dirty water out of the fish tank." An instruction on draining an aquarium.
Memory hook
Siphon sounds like 'sigh'—imagine the pipe taking a deep breath and sucking the water up and out. Siphon: Pulls water up and over.
When not to use
Do not use 'siphon' to describe simply pouring water out of a cup; it requires a tube and a height difference.
Fun facts
- The siphon effect is what makes modern flush toilets work; without it, toilets would require mechanical pumps to empty the bowl.
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