Verbs ending In -ize, -ise, -yze, and -yse

Many verbs that end in -ize can also end in -ise in British English. For example, in British English, all of the following spellings are acceptable: finalize/finalise; organize/organise; realize/realise. In American English, the only correct spellings are finalize, organize, and realize.  

In both American and British English, there is a small set of verbs that must always be spelled with -ise at the end. The main reason for this is that, in these words, -ise is part of a longer word element rather than being a separate ending in its own right. For example: -cise (meaning 'cutting) in the word excise; -prise (meaning 'taking') as in surprise; or -mise (meaning 'sending') in promise.

chastisedisguiseprise (meaning ‘open’)surprise


There are also a few verbs which always end in -yse in British English.



In American English, they are all spelled with the ending -yze


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