Definition of "crass"

You guys would rather be with someone else who’s equal to your status in life. Tiger Woods, or somebody. I comes across as crass, a Neanderthal, a babbling idiot sometimes. I like to show you that person. I like that person.

2002, Mike Tyson to the Media

The Albanians have a world ranking of 58, but even a side of fairly modest talents would surely have taken advantage of the kind of crass mistakes that Scotland made on Friday.

2018 September 7, Tom English, “Scotland 0-4 Belgium”, in BBC Sport‎

One may very easily fall into mistakes and errors when one is searching into the hidden causes of things, in the absence of real experiments, and this is easily apparent from the crass error of Cardan; who deems himself to have discovered the distances of the centres of the cosmos and of the earth through a variation of the magnetick iron of 9 degrees.

1900, William Gilbert, chapter 11, in On the Magnet‎