Words ending in OUR have been changed to OR in America (see COLOUR)
Words ending in IOUR have been changed to IOR in America (see BEHAVIOUR )
Many words ending in YSE or ISE have been changed to YZE or IZE in America (see ANALYSE, CATEGORISE, STANDARDISE) Exceptions: ARISE, DEVISE (This American spelling is also acceptable in the UK)
Many words ending in YSED or I SED have been changed to YZED or IZED in America (see CATEGORISED, STANDARDISED) (This American spelling is also acceptable in the UK)
Many words ending in ISATION have been changed to IZATION in America (see CATEGORISATION, STANDARDISATION) (This American spelling is also acceptable in the UK)
Words ending in RE have been changed to ER in America (see CENTRE, METRE)
Words containing the silent letters OUGH have been changed to in America so they are spelt phonetically (see DOUGHNUT, HICCOUGH)
Words containing a double consonant before ING and ED have been changed to one consonant (see TRAVELLING) (This American spelling is becoming acceptable in the UK)
Words which vary in spelling according to whether they are nouns or verbs have been standardised in some cases. eg: verbs: PRACTISE, LICENSE (NOTE: the word standardised follows the ISED rule above)
Words containing ae together (originating from Latin and often joined /æ/) as in Caesar, haemorrhoids
North American spellings are simplified for words containing letters which can be removed without changing the pronunciation. eg:ALUMINIUM, SMOULDERING
North American spellings are changed to simplify the spellings of some words eg: AEROPLANE, GAOL thereby making the spellings more phonetic
Where there are two spellings for one word, only one version is adopted in North America eg: EARNT, EARNED
Compound words are often either hyphenated, or written as two words eg: AEROPLANE
