Words ending in -ise and -ize

Many English words can be spelt with either –ise and –ize. In American English, the spelling with –ize is preferred. In British English, both forms are usually possible.

Examples are:

British English American English
Realize / realise Realize
Mechanize / mechanise Mechanize
Computerize / computerise Computerize
Baptize / baptise Baptize

Some words have –ise in both British and American English. Examples are:

Surprise; revise; advise; comprise; despise; compromise; exercise; supervise; televise; advertise

In American English advertize is also sometimes possible.


Capsize has –ize in both British and American English.

If you are in doubt, remember that in British English the forms with –ise are almost always possible.

Adverb formation

We normally change an adjective into an adverb by adding –ly.

Real – really
Definite – definitely
Pale – palely
Complete – completely
Right – rightly

There are some exceptions to this rule.

True – truly (NOT Truely)
Due – duly
Whole – wholly
Full – fully

Y and i

-y usually changes to –i

Happy – happily
Easy – easily
Dry – drily or dryly
Gay – gaily

Exceptions are:

Shy – shyly
Sly – slyly
Coy – coyly

Adjectives ending in consonant + le

-le changes to –ly after a consonant.

Idle – idly
Noble – nobly
Able – ably

Adjectives ending in ic

If an adjective ends in –ic, the adverb ends in –ically.

Tragic – tragically
Phonetic – phonetically

Note that public is an exception to this rule.

Public – publicly