Decimate means reduce by a large amount. I think it's the only word in the English language which does mean that, which makes it extra precious.
I'm not agreeing with those who insist that decimate must be used only in its original meaning (which was a system of punishment which involved one randomly selected Roman soldier in ten being killed by his nine comrades). That would shut up a valuable word in a box where it's not going to get a lot of daylight.
I can't see anything wrong with something like the string section of the orchestra was decimated by flu.
I can't see why decimate must always refer to humans, either. Oliver Cromwell came up with a decimating ten per cent tax in 1655. I don't know if it was understandable thing to do, but it was certainly comprehensible.
On the other hand, using decimate to mean destroy or hurt weakens a valuable word of unique meaning, and people who do this deserve to have their belly buttons invaded by palsied dust bunnies.
That's people who write stuff like: the muggers physically decimated him.
Or: when I found out it wasn't fancy dress after all I was, like, totally decimated.
Decimate. It means reduced by an important amount.
Otherwise use annihilate, embarrass, destroyed, devastated...
Word To Use Today But Only If The Circumstances Demand It: decimate. This word comes from the Latin word decimāre, from decem, ten.
If you're hung up over the ten bit I suggest you channel your energies into a campaign to get December reinstated as the tenth month of the year.