-ize Also -ise, -ization and -isation, -izer and -iser.
[French -iser, via late Latin -izare from Greek verbs ending in -izein.]
Verbs in this ending are a large and diverse set. Very broadly, one group is of verbs that take a direct object, which describe acting on something or treating it in a given way, so causing it to change its state (baptize, computerize, dramatize, fossilize, oxidize, pasteurise, privatize, sterilize, terrorize). A second set, of verbs that do not take a direct object, refers to following some line of behaviour, action, practice, or policy (agonize, apologize, extemporize, moralize, realize, theorize).
In French, the spelling is uniformly -iser and this has influenced English spelling. In the US the z form is standard, but in Britain spellings with z are largely restricted to formal and academic usage; elsewhere in the English-speaking world, -ise is usual. Whatever policy is adopted, some verbs must be spelled in -ise, including advertise, advise, arise, chastise, despise, disguise, exercise, revise, and surprise.
The ending is commonly used to make new verbs from adjectives or (especially) nouns and has done for centuries. In the twentieth century some people have objected to new forms such as finalize, prioritize, or hospitalize. However, such formations are now widely accepted, and new ones appear as needed (incentivize, medicalize, strategize, technologize), though not always with hopes of long-term survival (angularize, flexibilize, graffitize, radarize). Many apparently new forms, such as ceremonialize and novelize, actually have a long history.
These verbs frequently have related abstract nouns in -ization (criminalization, fertilization, liberalization, optimization, rationalization) though in the case of some modern examples, the noun came first and the verb was derived from it. See also -ation, -ition, and -ion.
Action nouns are formed in -izer: atomizer, fertilizer, memorizer, sympathizer, womanizer. See also -er1.