what is a quintile?

Today a family member asked me about a word in The Age newspaper - quintile. I asked her to read the sentence containing the word and she read:

The preliminary results showed the richest quintile of households received about 12 per cent of social assistance benefits while the second richest quintile got 11 per cent. 

I sounded like the word quartile, which I knew had something to do with quarters. [Here's the definition from Math Dictionary.] So I suggested quintile might relate to fifths.

And it does. The opening line of the article in The Age said:

The richest fifth of households receive nearly half of all the wages paid in Australia - but also get about 12 per cent of all government handouts, new research by the Bureau of Statistics show. 

Here's a more exact definition of the word from the Merriam-Webster 

now I'm officially a word buff

I learn so much from my regular email from 'A Word a Day' that I've decided to contribute a little to this excellent organisation. So today I became an official 'Word Buff' and I received this multilingual thank-you note:

Thanks, merci (French), gracias (Spanish), dhanyawad (Hindi), danke(German), efharisto (Greek), toda (Hebrew), grazie (Italian), arigato (Japanese), gratias tibi ago (Latin), khawp khun (Thai), takk (Faroese), mahalo(Hawaiian), dziękuję (Polish), mulțumesc (Romanian), spasibo (Russian), salamat (Tagalog), shukran (Arabic), köszönöm (Hungarian), obrigado(Portuguese), děkuji (Czech), ďakujem (Slovak), dankon (Esperanto), ...