Why does /usr/share/dict/words contain “manbird” on OS X?

Since some might miss the comment linking to it, I want to highlight this related question as well: Who or what compiled /usr/share/dict/words?

According to Wikipedia [1]: "In 1934, the New International Dictionary was revised and expanded for a second edition, which is popularly known as Webster’s Second or W2, although it was not published under that title."

[0] https://unix.stackexchange.com/questions/286787/who-or-what-...

[1] https://en.wikipedia.org/wiki/Webster%27s_Dictionary#Webster...

I am using the wcanadian-insane wordlist under Linux, and it is also in there.

First I thought it would be related to ladybird, which is another common name for the ladybug. But after a few pages of internet meme crap, I discovered manbird is the same as birdman - an aviator.

When I think of birdlady, I can't help thinking of Kids In The Hall https://www.youtube.com/watch?v=0YwnAdT9I_o