To understand the exotic-seeming etymology of gazebo, you need to understand the Latin suffix -bo. Any verb ending in -o refers to the first person, and -bo is the future tense for the first person. And the root of the word is the English word gaze (as in "I shall see"), making gazebo a linguistic mongrel from two different languages, something that's quite rare. The reason for this appellation was a humorous allusion to how you can gaze out on the surrounding landscape while in a gazebo. Or so we think: there was no explanation provided for its first usage in a 1752 book called New Designs for Chinese Temples. Assuming this is correct, gaze is of Scandinavian origin and was a verb well before a noun: it is likely connected to Old Norse ga, which meant "to heed" (also the source of gawk), from Proto-Indo-European ghowe, "to honor". Other theories for gazebo's etymology include something from Chinese or Arabic- it's all very iffy.
The word pismire has experienced a two hundred-fold decrease in usage since its peak in the early 1800s. A very large majority of people today don't even know that it's an archaic word for "ant". And of those who do know, even less are aware of the fact that it's kind of redundant! It's a portmanteau of two words: pyss, meaning "urine" (and, yes, the forebear of modern piss), and mire, ironically also meaning "ant". So an old word for "ant" comes from "piss ant", making the pyss part completely useless. The connection to urine was apparently because of the pee-like smell of anthills. Now, mire comes from Old Norse maurr or myrr, with the same meaning. Then, through Proto-Germanic miuzijo, we can reconstruct it to Proto-Indo-European morwi, yes, still with the same definition. Now we just have to etymologize the word piss! It was a verb before it was a noun (and this transition is a fine instance of anthimeria). This comes from Old French pissier, from Latin pissiare, which also still meant the same thing. Allegedly, this is of imitative origin, meaning that the verb pissiare is supposed to sound like the action of micturition.
Marshmallows originally came from the mallow plant, which grows in marshes. That's basically what the etymology boils down to. However, it's not that simple because the portmanteau occurred more than a thousand years ago: in the times of Old English, back when marshmallows were very different from today, the word was merscmealwe, from the Old English words mersc for "marsh" and mealwe for the plant. Mersc, through Proto-Germanic marisko, comes from the Proto-Indo-European root mori, which was designated to any body of water. Mealwe, meanwhile, actually takes an Italic route, deriving from Latin malva, meaning "mallow" as well. This has a Greek cognate, but cannot be accurately reconstructed to PIE. An obscure Mediterranean language is hypothesized as the origin. Usage of the word marshmallow steadily increased through the twentieth century due to increased commercial availability, with today having the highest utilization ever.
Jodhpurs are the type of pants that jockeys wear when they race horses (singular is jodhpur, but it's pluralized just like the word pants), ideal for hip motion while riding. Interestingly, they come from India, and were brought into English culture when a delegation led by Sir Pratap Singh, a prince in the Jodhpur state, came to visit Queen Victoria and really impressed the gentry with the exotic new fashion. Within years, every jockey in the UK was wearing jodhpurs, and to this day it is still the norm in horse riding circles. And, yes, you read that previous sentence correctly: the delegation was from a state called Jodhpur (it no longer exists). The pants were named after the region. This comes from a local city, Jodha, which was named after Rao Jodha, who founded the city as a highly defended capital. There's a Wikipedia page on him and he's really interesting (the classic underdog story); check it out! But now you know.
The word placebo first crops up in the Bible! In medieval translations of Psalms, placebo was used as a Latin word meaning "I will please", in a sentence that iterated how "I will please the Lord in the land of the living." Later on, an application of this definition for something placating gave us the "fake substance" meaning we use today (placating, by the way, is distantly related to the word placebo, as is please). Placebo is a conjugation of placeo, which simply meant "I please". That in turn can be reduced to the infinitive placere, or "to please", which is from placare, or "to soothe" (here's that connection to placate), because soothing thins are pleasing. Placere could trace to plehk, a Proto-Indo-European reconstruction also meaning "to agree", but there are a few other proposed sources, including a word for "flat". It all depends on the ablauts. So after all that Bible stuff, the word placebo was coined in the 1200s and placebo effect in the 1900s.
Adam Aleksic, a freshman studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, and law.