Filter

How to spell filter

6 letters · 2 syllables

How to pronounce filter

Say the part in capitals loudest.

What does filter mean?

1. nounA device or material that removes unwanted substances or signals from something passing through it.
2. verbTo pass something through a device or process that removes unwanted parts.

Filter in a sentence

• noun

  The coffee machine needs a fresh paper filter each morning.

• verb

  You should filter the tap water before topping up the aquarium.

• noun

  A clogged air filter will reduce the engine's performance.

• verb

  The software can filter out spam before it reaches your inbox.

Where does filter come from?

Language of origin: Latin

The word comes from the Medieval Latin filtrum, which named a pad of felt that was used to strain liquids, since wine and other fluids were poured through matted wool to clear them of sediment. That Latin term itself was borrowed from a Germanic source related to the word 'felt', describing the densely packed fibres that made the material effective for straining. French took it up as filtre, and English adopted it in the late 1300s, first in the verb sense of passing a liquid through such a material. Over the centuries the meaning broadened well beyond felt: any device or process that removes unwanted material came to be a filter, and the word now covers everything from coffee makers to photographic lenses to software that sorts data. The single 'l', single 't', and the '-er' ending are the spelling points to watch, since the word looks regular but is sometimes muddled with the rarer 'philtre'.

How the word is built

• filter (from Medieval Latin filtrum: a piece of felt used for straining)
• no productive affixes in modern English