How to Rename or Define
When constructing a sentence in which a term or concept is described in other words or a meaning is given, use these guidelines for punctuating the parenthesis.
When using namely, which establishes that one or more examples or names of a thing will be provided, or employing phrases that serve a similar purpose (such as “for example” and “that is”), always follow the word or phrase with a comma. The punctuation preceding the word or phrase depends on the structure of the sentence.
(The abbreviations e.g. and i.e., representing Latin phrases equivalent to “for example” and “that is,” respectively, are discouraged in formal prose in favor of the English phrases except in parentheses or in notes; use the same surrounding punctuation for the abbreviations as for the phrases.)
When what follows is a simple phrase and not an independent clause, precede namely and the like with an em dash to signal that one is transitioning from discussing something to providing examples about it: “Constitutional law defines the interrelationships between various branches of government within a state — namely, the executive, the legislative, and the judicial.”
Alternatively, enclose the additional information in parentheses: “I enjoy reading nineteenth-century historical adventure novels (for example, those by Sir Arthur Conan Doyle, Sir Walter Scott, and Robert Louis Stevenson).”
If the word or phrase, and what follows, is an independent clause, start a new sentence or precede the word or phrase with a semicolon:
“I agree with what you said. That is, I agree if I understand what you meant.”
“I agree with what you said; that is, I agree if I understand what you meant.”
An em dash may be used in place of the period or semicolon to signal an abrupt addition to the preceding statement, or use parentheses to represent an afterthought.
Another option, in place of using namely, is to employ a colon, which among other purposes is used to indicate an expansion or explanation: “Constitutional law defines the interrelationships between various branches of government within a state: the executive, the legislative, and the judicial.”
“For example,” “that is,” and similar phrases can be used following a colon or an em dash:
“I enjoy reading nineteenth-century historical adventure novelists: Sir Arthur Conan Doyle, Sir Walter Scott, and Robert Louis Stevenson, for example.”
“I enjoy reading nineteenth-century historical adventure novelists — that is, writers like Sir Arthur Conan Doyle, Sir Walter Scott, and Robert Louis Stevenson.”
(Either phrase can precede or follow the examples, but “for example” usually comes at the end and “that is” usually appears at the beginning.)
Use of “in other words” as a transitional phrase follows these patterns (the particular method of punctuation depends on the context specific to a sentence):
“We have insufficient funds to continue operating — in other words, we are broke.”
“We have insufficient funds to continue operating. In other words, we are broke.”
“We have insufficient funds to continue operating; in other words, we are broke.”
“We have insufficient funds to continue operating. (In other words, we are broke.)”
One similar point about punctuation is how to provide a gloss, or a brief definition, as I’ve done in this sentence for the word gloss: Set the gloss off from the term with a pair of commas. Alternatively, enclose the gloss in parentheses, especially if the gloss is a translation: “The word is chico (“boy,” “child,” or “small”).”
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