Decimate

The Merriam-Webster Online Dictionary defines the word 'decimate' as follows:

1 : to select by lot and kill every tenth man of
2 : to exact a tax of 10 percent from (poor as a decimated Cavalier -- John Dryden)
3 a : to reduce drastically especially in number (cholera decimated the population) b : to cause great destruction or harm to (firebombs decimated the city)

Etymology: Latin decimatus, past participle of decimare, from decimus tenth, from decem ten

The origin of this word is fascinating, if a little barbaric. When a unit of the Roman army proved cowardly, treacherous, or insubordinate, one soldier of every ten was selected and executed as an example to the others. The practice apparently proved quite useful in instilling discipline and enforcing the chain of command.

For some reason, the origin of this word came unbidden to my mind just after my fifth period Algebra I class yesterday.

Hmmm....