An agentive ending in the English language

English language

English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 is the use of the suffix

Affix

An affix is a morpheme that is attached to a word stem to form a new word. Affixes may be derivational, like English -ness and pre-, or inflectional, like English plural -s and past tense -ed. They are bound morphemes by definition; prefixes and suffixes may be separable affixes...

 -er, -or, -ist, or -ian at the end of a verb

Verb

A verb, from the Latin verbum meaning word, is a word that in syntax conveys an action , or a state of being . In the usual description of English, the basic form, with or without the particle to, is the infinitive...

 in order to create a noun

Noun

In linguistics, a noun is a member of a large, open lexical category whose members can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition .Lexical categories are defined in terms of how their members combine with other kinds of...

meaning "someone or something that does the action the verb describes." The corresponding suffixes are called agent suffixes.

Examples include provider (from provide) and builder (from build), pianist and librarian.

There is no systematically clear distinction between the ending chosen for a person who does the action and for a machine that enables the action to be performed: though there is a distinction between a typewriter (machine) and a typist (person), a cleaner can be a washing substance or a person who scrubs with it.