修辞格，也叫做辞格，它是修辞学研究的重心。英语中修辞格一般称作“figure of speech”，也称“rhetoric device”，“figurative language”，“rhetoric skill”，“rhetorical figure”等。
《美国传统英语词典》的定义是：“An expression that uses language in a nonliteral way,such as a metaphor or synecdoche,or in a structured or unusual way,such as anaphora or chiasmus,or that employs sounds,such as alliteration or assonance,to achieve a rhetorical effect.”
《大英简明百科》的定义是：“Form of expression used to convey meaning or heighten effect,often by comparing or identifying one thing with another that has a meaning or connotation familiar to the reader or listener.An integral part of language,figures of speech are found in oral literature as well as in polished poetry and prose and in everyday speech.Common figures of speech include simile,metaphor,personification,hyperbole,irony,alliteration,onomatopoeia,and puns.”
《哥伦比亚百科全书》的定义是：“Intentional departure from straightforward,literal use of language for the purpose of clarity,emphasis,or freshness of expression.See separate articles on antithesis; apostrophe; conceit；hyperbole; irony; litotes; metaphor; metonymy; paradox; personification；simile; and synecdoche.”
《韦氏词典》的定义是：“A form of expression（as a simile or metaphor）used to convey meaning or heighten effect often by comparing or identifying one thing with another that has a meaning or connotation familiar to the reader or listener.”
维基百科（Wikipedia）给出的定义是：“A figure of speech is a use of a word that diverges from its normal meaning,or a phrase with a specialized meaning not based on the literal meaning of the words in it such as a metaphor,simile,or personification.Figures of speech often provide emphasis,freshness of expression,or clarity.However,clarity may also suffer from their use,as any figure of speech introduces an ambiguity between literal and figurative interpretation.A figure of speech is sometimes called a rhetoric or a locution.”
汉语中，也对修辞格下了很多定义。唐钺在《修辞格》（1923）中给修辞格下的定义是：“凡语辞中因为要增大或者确定词句所有的效力，不用通常语言而用变格的语法，这种地方叫做修辞格。”张弓在《现代汉语修辞学》（1963）中明确指出：“修辞方式是适应社会交际的需要，根据民族语言的内部发展规律创造的具体的一定的手法，是语言艺术化的手段。”吴士文在《修辞格论析》（1986）中详尽地介绍了各家的定义，最后提出了他自己的定义：“辞格是在言语活动中长期形成的具有特定功能、特定结构、特定方法、符合特定类聚系统的模式。”谭永祥在《修辞精品六十格》（1993）一书的开头就给修辞格下了如下定义：“辞格是具有表现力的，在形式或意义上具有一定规律性的审美化的语言。”这个定义鲜明地突显了修辞格的特色，即具有审美效果的语言才是修辞格。