Instancing Lines of Text

[Krizzzle]

I work with many very large InDesign documents that have several cases of text that is duplicated throught it. My question is, is there a way to make an instance of lines of text, or multiple sentences, that I can then just place with in the document, that will also update and change if the master text changes? I know this can be done with objects, but I need to be able to use sentences within a text box with alot of text. A small example woud be, if I have a text box with a glossary containing several definitions, I want one specific defintion to appear everywhere the term does throughout the documents and also have them update when the master definition changes. Im not sure if this can be done, I have done an extensive amount of research on this, and cant seem to get InDesign to do exactly what I want. It would work similar to a cross-reference I would suppose. 

[Jens Trost]

You can link textframes and their content. Maybe that's what you're looking for:
Select a textframe and then go to Edit -> Place and Link

After that your textframes appear in the Links Panel. If you change you're master textframe it's like an normal link and shows you the yellow rectangle to update the link.

[Jens Trost]

Another solution would be with text variables
https://helpx.adobe.com/indesign/user-guide.html/indesign/using/text-variables.ug.html

[Eugene Tyson]

You got 2 excellent answers! can you please tick the answer that works for you or let me know and I'll mark them as correct.

Thanks! 

[Barb Binder]

I need to be able to use sentences within a text box with alot of text

I would advise against the use of variables for this situation—InDesign variables still can't break across lines. ☹️

~Barb