Update: Got more words and now its clear these words don't even have a spot on the word list at all. I'll try and list them all here.
Words without a spot on the word list:
Genocide
Time
Homicide
Magic
Parent
Sibling
Child
Family
Transportation
Law
Crime
Punishment
Easter
Valentines
Mistletoe
Thanksgiving
Noise
Suicide
Politics
Night
Anime
Earth
Gospel
Paradise
Festival
Freedom
War
Sacrifice
Belief
Bias
Boy
System
Music
Song
Sexuality
Gender
Hollow
Slime
New Years Day (? Horu calls me a psycho for typing this, but the hint is obvious)
Food
Media
A slang term for food (Don't know quite which word)
A slang term for honesty (I might be very bad at slangs)
A slang term for charisma (I also miss one word with a Be, so one of these three might be present on the last after all)
Keep in mind that I have the Deluxe version, update 0.3.00, and as I just noted, I miss a single word starting with Be.
Also note that you will know the word you got isn't on the word list if you don't get a little notification about having found a new cup in the upper right corner.
And lastly, there might be more words, but at this point I keep getting the same hints over and over so I'm giving up for now.
Speculation: It feels like there are ~40 unregistered words, which would be about the same as update 0.3 added in total. Word list for 0.4 leaked early?