What is a synomyn for the?

There isn't a single perfect synonym for "the," as it's a definite article and its meaning is highly dependent on context. However, here are some options depending on the situation:

For specific items:

* That: "I bought that book you recommended."

* This: "This is the best pizza I've ever had."

* These: "These are the shoes I was looking for."

* Those: "Those are the keys I need."

* The particular: "The particular book you need is out of stock."

For general references:

* Aforementioned: "The aforementioned book was written by a renowned author."

* Said: "Said book is a bestseller."

For emphasis:

* Very: "This is the very book I've been searching for."

* Specific: "Let's look at the specific example you mentioned."

In some cases, you can simply omit the article altogether:

* "I like book you recommended" (instead of "I like the book you recommended").

Ultimately, the best substitute will depend on the specific context and what you're trying to convey.