[yeleti]

A long long time ago (in 2010), Facebook sued a start-up called Teachbook for using 'book' in its name. Hope you don't get into that muddle.

https://money.cnn.com/2010/08/26/technology/teachbook/

[lioeters]

I hadn't heard about this. They've sued several companies whose names end with "book". Apparently a lawsuit coming from FB is scary enough that they've acquiesced and changed their names, without standing up in court. Replacebook!