A different (Read wrong) system of spelling the English language used by citizens of the United States who cannot be bothered to learn the correct spelling of simple words.
usually involves missing out letters, switching the order or just using the complete wrong word
closest comparison can be asking a small child to spell a word and making a dogs ears of it.
English spellings: Colour, Centre, Honour, Draught
American English spellings: Color, Center, Honor, Draft