The color sepia has a rotten origin. The term, which either describes a color or a kind of muted brown filter used in photography and social media, actually comes from the Latin word sepia, originally. This, surprisingly enough, meant "cuttlefish", the connection being that the cephalopod (a relative of the squid) releases a dark brown ink used by the classical Mediterranean civilizations. Not much changes as we trace it back further to the Greek word sepia, with the same meaning, but here it gets interesting. Possibly through the name for another disgusting aquatic animals, seps, this appears to have roots in sepein, meaning "to become rotten", because the seps animal's bite could cause infection. Here the origins get really obscure, but it might have connections to other words to do with rottenness, like Ancient Greek for "sore" and "decay". Despite all the online use, the word sepia has decreased in usage over the past few decades.

You know when you buy a book, but never have time to get to read it, and eventually it ends up perpetually lying on a bookshelf with no end in sight? There's a word for that. Tsundoku is a noun describing exactly that, when unread tomes get lumped together. It originated in the late 1800s in Meiji-era Japan, from a verb, ​tsunde oku, which meant "to pile up". But how did this get applied to books? Through a pun! Yep, even in old-timey Nippon they had senses of humor: the 'de oku in tsunde oku sounds like the word doku, meaning "book", so it got applied to books. Later, the cumbersome word was shortened to something a little more manageable, or tsundoku. Now, tracing the etymology of tsunde oku, the first word might come from a term meaning "pinch", through a connection of "hold", and oku meant "inside". As I've explained before, etymologizing Japanese, Chinese, and the like is difficult because the origins are obscure and the letters and meanings come from different places.

Many strict Christians will tell you that Jesus is their companion, and then they'll go off to break some bread and honor him by taking him inside themselves even more. That's oddly appropriate, etymologically speaking. The word companion, through Middle English and Old French, comes to us from the Latin word companionem, which literally can mean "bread buddy". This is because those zany Romans consider anybody you break bread with to be a "companion", and therefore the word was created. This is a portmanteau of com, meaning either "with" or "together", and panis, which was the Latin word for bread and the source of many similar-sounding words that we know today. Com-, through the earlier prefix cum-, comes from the Proto-Indo-European root kom, which meant something more like "beside". Meanwhile, panis may be from Proto-Indo-European peh, or "to graze", since animals graze on wheat, and wheat makes bread. All of this is very convoluted and inherently fascinating.

Right now, many people use the word xerox as a verb meaning "photocopy" in general. Most of us know that it's also a trademark: as a noun, Xerox was legally claimed by the Haloid Company in 1952. You'd think the company would be thrilled with its product name passing into public use, because they would force other corporations to use generic names while strengthening the reputation of their company, but the Haloid Co. thought differently. You see, if a judge rules that a name becomes too generic, the trademark can be lost, so Haloid actually has fought pretty bitterly against using Xerox as a verb. Anyway, back when they formed the word, it was meant as a cool-sounding modification of xerography, the name for a photocopying process, and a term only coined four years before Xerox itself. This is a portmanteau of Ancient Greek xeros, meaning "dry", and -graphy, that common suffix for something written- so, xerography means "dry writing", which sort of makes sense. Xeros comes from the Proto-Indo-European root kseros, with the same meaning, and -graphy comes from the Greek root graphein (or "writing"), from Proto-Italic grupho, from Proto-Indo-European ​gerbh, meaning "to carve". Now you know.

The word ostrich is named after three different types of birds, as well as the word bird itself. Through Anglo-Norman ostrige via Old French ostruce, ostrich has roots in the a Latin portmanteau of the words avis, meaning "bird", and struthio, meaning "ostrich". So the word ostrich is kind of redundant in that it actually means ostrich bird. Cool. Avis has a boring etymology: from Proto-Italic awis, from Proto-Indo-European hewis, still meaning "bird". It's struthio that's interesting. It comes from the Greek word struthion, which meant "ostrich", from the earlier Greek word struthos, which meant "sparrow" (apparently ostriches look like big sparrows to the Greeks), probably from Proto-Indo-European trozdo, which meant "thrush". The Greeks called the ostrich a struthokamelos, or "camel-sparrow", again because of its size. Approximately 1 in every 100,000 words written down is "ostrich", and usage has been declining since the mid-1800s.

In the first century CE, physician Aretaeus of Cappadocia coined the word diabetes to describe a condition characterized by an abundance of urine. As this is one of the main symptoms of the modern disease, the word became applied for it. When Arataeus used the word, it originally meant "passing through". You can probably figure out the metaphor there. This is a portmanteau of the prefix dia-, which means "through", and the verb bainein, which meant "to walk" (a definition which later shifted to "pass", obviously). The former is from the Proto-Indo-European root dwo, meaning "two", and the latter is from another PIE root, gwo, or "come". So I guess diabetes is technically the Second Coming? Maybe not, but that's pretty sweet. You know what else is sweet? The official, scientific name for diabetes is diabetes mellitus, and mellitus comes from the Latin word for "honey". And the reason for that is really weird. The guy who added mellitus to the name was the English doctor Thomas Willis, who noticed that the urine of diabetics is unnaturally sweet. Go figure.