Definition of decimate transitive verb
1 : to select by lot and kill every tenth man of a regiment
2 : to exact a tax of 10 percent from poor as a decimated Cavalier
Not the 90% mentioned
And so then the definition 3 does not exist? It is not there because you don’t like it? I have no clue why folks think they can cherry pick or redefine. It is a real problem and what the left does all the time.
Depending on application ALL the definitions of a vocabulary word are acceptable options. Not just one or two in the list. Or self invented definitions that are not even there.
As used in this OP definitions 3-a and 3-b absolutely do apply as it was used. It is a pet peeve that so many do this, especially the left with deceptive redefinition for propaganda purposes.