Decimate is from Latin decimat- ‘taken as a tenth’, from the verb decimare, from decimus, which meant the "the removal or destruction of one-tenth".  What offences could lead to the Romans use of decimation, or the killing of every tenth man or one tenth of a unit?  Decimation was an extreme punishment for the most serious transgressions, such as cowardice, insubordination, desertion and mutiny.  The mere threat of decimation was designed to ensure that soldiers adhered to military discipline.  In Middle English the term decimation denoted the levying of a tithe, and later the tax imposed by Cromwell on the Royalists (1655).

According to the Oxford English Dictionary, the verb "decimate" was first used in English in the late 1500s, specifically in 1591. It was borrowed from the Latin word decimatus, which is the perfect passive participle of decimō (meaning "to kill one tenth" or "to tithe").  In modern English, "decimate" is most commonly used to mean "to severely damage or destroy" or "to greatly reduce in number," reflecting the broader sense that has developed over time.

Examples of using "decimate" in a sentence: 
"Yet both dam projects would decimate the very scrubland the lynx depends on." 
"This kind of moth is responsible for decimating thousands of trees in our town." 
"Budget cuts have decimated public services in small towns."
"Bouts of large-scale logging decimated close to a third of their forest in the 1980s." 
"If something is drastically reduced or killed, especially in number, you can say it was decimated." 
"The oil spill in the Gulf of Mexico decimated the wildlife along the coast." 
"Silber says the tax rollback would decimate basic services to the needy by ten percent." 

I have to admit that decimate is one of the words I love seeing people argue about. It's up there with what's the plural of octopus and platypus.  

I entirely agree with the Mirriam-Webster comment The word decimate is what we might delicately refer to as a problem word. It seems to invite spleen, at least on the part of a small but committed group of linguistic enthusiasts who feel that it is often misused. 

While in Latin usage decimate means to eliminate one in ten there is little to support the argument that this meaning also applies in English usage. For example, none of the examples of decimate being used in a sentence that @Bill W has posted use decimate in the sense of one in ten. 

While there is a strident group I would call "language purists" who insist decimate should only be used to describe destruction by one tenth, there is little, well actually no, evidence that decimate is generally used with that meaning in English and probably never was generally used in English with that specific meaning.

Of course, it's now obvious I've joined the group of people who argue about decimate. 

2 hours ago, Paladin said:

I have to admit that decimate is one of the words I love seeing people argue about. It's up there with what's the plural of octopus and platypus.  

I entirely agree with the Mirriam-Webster comment The word decimate is what we might delicately refer to as a problem word. It seems to invite spleen, at least on the part of a small but committed group of linguistic enthusiasts who feel that it is often misused. 

While in Latin usage decimate means to eliminate one in ten there is little to support the argument that this meaning also applies in English usage. For example, none of the examples of decimate being used in a sentence that @Bill W has posted use decimate in the sense of one in ten. 

While there is a strident group I would call "language purists" who insist decimate should only be used to describe destruction by one tenth, there is little, well actually no, evidence that decimate is generally used with that meaning in English and probably never was generally used in English with that specific meaning.

Of course, it's now obvious I've joined the group of people who argue about decimate. 

  

There, I corrected by entry in response to your complaint. 

56 minutes ago, drpaladin said:

Was it a complaint?

Maybe not of me directly, but in how the definition of decimate has drifted from its original meaning.  I thought I'd appease him, nonetheless.  

7 hours ago, Bill W said:

There, I corrected by entry in response to your complaint. 

Not a complaint @Bill W. I was just using it to illustrate my point that we normally use decimate to mean destroy in a general way and not in the specific one in ten sense.