RE: Standard English
Standard English is the English spoken by native English speakers - as opposed to Queen's English or Poncy Pedant's English.
Do you not see the irony of your claiming a meaning in English by quoting a foreign language?
Anyway, many words in English do not technically mean what the user thinks they mean, but as the listeners think it means what the user thinks it means then in reality it does actually [in standard English] mean what the user thinks it means.
As a number of examples:
Broadband - = high throughput even though typically it is baseband and not broadband
Bad / sick / awesome etc - usage rarely meets dictionary definition
Gay - doesn't mean "happy" any more. Although to be fair most of the people I know who identify themselves as gay are generally rather cheerful souls.
Pirate - even though pedants try to separate galleon based raping murderers with wooden legs, eye-patches and parrots from spotty freetards who don't want to pay for shit, the general public, when presented with the word "piracy" thinks of music downloading.
and so on. However if you check your favourite dictionary (or http://www.oxforddictionaries.com/definition/decimate?view=uk if you can't be arsed) you will see that the primary meaning for "decimate" is "to kill, destroy or remove a large proportion of".
Welcome to the 21st century - I am sure you will come to love it in time.