Well, it depends how you are getting the item.

If you are getting it via the URL like this:

/_api/lists/getbytitle('News')/items(50)

Where the number in the brackets "(50)" is the item ID you can get an item e.G. like this:

/_api/lists/getbytitle('News')/items?$filter=Title eq 'FAQ'

So the URL is looking for an item, where in the title column FAQ is the content.

In general:

/_api/lists/getbytitle('<ListName>')/items?$filter=<InternalColumnName> eq '<Value>'

Hope this could help.

Well, it depends how you are getting the item.

If you are getting it via the URL like this:

/_api/lists/getbytitle('News')/items(50)

Where the number in the brackets "(50)" is the item ID you can get an item e.G. like this:

/_api/lists/getbytitle('News')/items?$filter=Title eq 'FAQ'

So the URL is looking for an item, where in the title column FAQ is the content.

In general:

/_api/lists/getbytitle('<ListName>')/items?$filter=<InternalColumnName> eq '<Value>'

To check the internal column names you can just use this:

/_api/lists/getbytitle('<ListName>')/items

Then use that name for the in the filter.