LONDON (Reuters) – If your mouldies are giving you the cringe then perhaps it's time you bought them this totally nang book.

A 13-year-old English schoolgirl has had a surprise publishing hit with "The A-Z of Teen Talk", a dictionary of teenage slang that's proving popular with parents and children alike.

With definitions for words such as "fudge" (a really stupid person), "nang" (cool) and "mouldies" (parents), the dictionary appears to be helping out-of-touch parents recommunicate with their lingo-obsessed offspring.

"It sort of helps bridge the gap," said Ingrid Parris of Ravette, the publishing house that picked up the book, sent in as an unsolicited manuscript by Lucy van Amerongen, a schoolgirl still sporting a "tin-grin" (someone who wears braces).

Van Amerongen came up with the idea after her parents complained they couldn't understand what she and her sisters, aged 11 and 23, were saying to one another.

She decided to ask friends at her private boarding school to come up with their best slang suggestions, which she then compiled into a 40-page book.

The publisher made an initial print run of 5,000 copies, but the mini-dictionary proved such a success in the run up to Christmas that a re-print of 6,000 is already on the cards.

Several words owe their origin to mobile phones and text messaging, such as "book", a synonym for cool which comes from the fact that if you try to text "cool" it comes up first as "book".

Here's a selection of words and their definitions:

Phat-free — uncool

Shizzle — someone you really admire, as in "she's a shiz"

Gratz — Thanks

Cringe — embarrassment, as in "your parents are a cringe"