Hackbraten is right. When I talk about dicts, I refer to a specific Python data type. Still, the truth is, I struggle to spell "dictionary." Even now, I copied the word from your comment.

Given how ubiquitous that type is, wouldn’t the four-syllable word “dictionary”, once written down hundreds of times, be prone to semantically satiating any discussion and code base?

Besides, you could argue it’s not exactly the author’s choice because `dict` is the actual name of Python’s dictionary type.