If your glossary has a definition for the term "widget", you can enter it as a term like this:
A ++widget++ is the fundamental building block of OSF/Motif user interfaces.
If the glossary entry is "widget", but you need to use the plural form within the sentence, you could enter the term like this:
<term "widget">Widgets<\term> are the fundamental building blocks of OSF/Motif user interfaces.
If you want to enter the same term, but you either don't want to include it in the glossary or you don't want it to be a hyperlink, use the nogloss parameter like this:
<term nogloss> Widgets<\term>are the fundamental building blocks of OSF/Motif user interfaces.
The equivalent short form is:
<term nogloss|Widgets| are the fundamental building blocks of OSF/Motif user interfaces.