\newglossaryentry

Synopsis, one of:

\newglossaryentry{label} 
{ 
  name={name}, 
  description={description}, 
  other options, ... 
}

or

\longnewglossaryentry{label} 
{ 
  name={name}, 
  other options ..., 
} 
{description}

Declare a new entry for a glossary. The label must be unique for the document. The settings associated with the label are pairs: key=value.

This puts the blackboard bold symbol for the real numbers ℝ, in the glossary.

\newglossaryentry{R}  
{  
  name={\ensuremath{\mathbb{R}}},  
  description={the real numbers},  
}

Use the second command form if the description spans more than one paragraph.

For a full list of keys see the package documentation on CTAN but here are a few.

name ¶

(Required.) The word, phrase, or symbol that you are defining.

description ¶

(Required.) The description that will appear in the glossary. If this has more than one paragraph then you must use the second command form given in the synopsis.

plural ¶

The plural form of name. Refer to the plural form using \glspl or \Glspl (see \gls).

sort ¶

How to place this entry in the list of entries that the glossary holds.

symbol ¶

A symbol, such as a mathematical symbol, besides the name.