Infiltration

How to spell infiltration

12 letters · 4 syllables

How to pronounce infiltration

Say the part in capitals loudest.

What does infiltration mean?

1. nounThe act of secretly entering a place, group, or organisation in order to gather information or cause harm.
2. nounThe gradual passing of a liquid or substance into something through small openings or pores.

Infiltration in a sentence

• The spy's infiltration of the rival company went undetected for months.

• Poor sealing caused water infiltration into the basement walls.

• Border guards reported the infiltration of armed men during the night.

• The survey measured rainwater infiltration into the surrounding soil.

Where does infiltration come from?

Language of origin: Latin

The word traces back to the Medieval Latin filtrum, which actually meant 'felt', the matted wool cloth that was used to strain liquids; from it came the verb meaning to pass a liquid slowly through such a material. French built the verb filtrer and then infiltrer, attaching the prefix in- 'into', to describe fluid seeping into something. English borrowed 'infiltrate' and the noun 'infiltration' in the eighteenth century, at first strictly for the slow seeping of water or other fluids through a porous substance. By the nineteenth and twentieth centuries the meaning had widened into the military and political sphere, describing troops or agents who slip quietly into enemy territory or an organisation, just as water soaks unseen through felt. The shared 'filt' core still links it to the everyday word 'filter', which is the memory hook for the tricky middle of the spelling.

How the word is built

• in- (into)
• filtr- (to pass through, from Latin filtrum 'felt used for straining')
• -ation (noun of action)