Re: That's the first time in a long time ...
It's not a Latin word, it's an English word.
The Latin root is "decimat", meaning removal of a tenth. The Roman army disciplinary action of drawing every tenth man by lot and putting them to death (not removal of hands!) was first called decimation in English around 1600. It was also briefly used in English similarly to the word "tithe", also starting in around 1600.
As a side note, most linguists consider the word to have mutated into the more common "utterly destroyed" meaning. Some of us pedants disagree.