To select by lot and kill every tenth man of. (Merriam – Webster)
To exact a tax of 10 percent from. (Merriam – Webster)
To reduce drastically especially in number. (Merriam – Webster)
To cause great destruction or harm to. (Merriam – Webster)
To destroy a great number or proportion of: (Dictionary.com)
To select by lot and kill every tenth person of. (Dictionary.com)
To kill a large number of something or to reduce something severely. (Cambridge Dictionary)
Kill, destroy, or remove a large proportion of. (Oxford Dictionaries)
Drastically reduce the strength or effectiveness of (something). (Oxford Dictionaries)
How do I decimate part of a mesh?
The Indianapolis Colts are Going to Decimate the Dallas Cowboys.
“Removal of a Tenth” – A Brief and Bloody History of Decimation.