In the book, Grace claims to have invented the word “Astrophage”. What does it really mean to invent a word and what other invented words are there in the novel?

One way we could find words invented for the book would be to compare all the words to a dictionary or spelling list. However, one immediately runs into issues.

Few dictionaries include proper names like “Stratt” or ”Ryland”. An English dictionary won’t contain foreign words like ”образец” or “甲板”. Numbers like “11,871” aren’t individually included, nor are symbols (which are unusually common in Project Hail Mary).

There are also words which may not be found in many dictionaries but which are straightforwardly derived from words that are. The early chapters of the book include words like “doublings”, “militaries”, and “supersonically” which were not found in the spelling lists we checked against. One would certainly not claim, however, that these words were invented by Andy Weir for the book.

Another category of words not found in lists are words spelled differently to convey a particular manner of speaking, for example “Lrmln” or “Craaaaaap”. There are also words that get interrupted such as “biowea”.

Manually going through and taking all these into account leaves words such as “Astrophage”, “Eridian”, or “Petrovascope”. These feel like they were made up for the novel but they are clearly derived from other words or components of words that are familiar.

Even more borderline are words like “nanosyringe” or “subcylinders” which may never have been seen by a reader before (and weren’t found in the lists we looked at) but whose meaning is immediately obvious.

All of this makes it nearly impossible to just list the invented words in Project Hail Mary. Even if there are words that cannot be found in any dictionary, they are not “invented” in the same way that, say, “miruvor” or “lembas” are in The Lord of the Rings.