The word ‘dog’ is interesting because it essentially has no etymology. It has no known cognates in English/Germanic/other Indo-European languages. It first showed up in Old English as dogca, referring to some sort of mastiff, but other than that nobody really has any idea at all where it came from.

Muscle comes from latin and means little mouse.

Tried and True.

To you it probably means “tested and found to be reliable/trustworthy.” An example, a few days ago the topic of a car without hydraulic brakes made the rounds. Hydraulic brakes on passenger cars are “tried and true,” we trust them, and are skeptical of a vehicle without them. But that’s not where the phrase originally came from; it’s a centuries old woodworking term.

This is a try square. An OLD tool; examples survive from ancient Egypt. It’s such a basic tool that it’s often used as the symbol of the carpentry trade. “Try” in this case means “examine” rather than “attempt”, more like how a judge “tries” a case than a jedi trainee “tries” to lift an X-wing out of a swamp. A try square is used to examine a board. For squareness, and possibly also straightness and flatness. A board that passes this exam is said to be “true.”

“True” meaning straight, flat, parallel or even concentric is still in use to this day; “truing” a surface means to flatten it.

“Helicopter” isn’t heli - copter

It’s helico - pter.

Helico: Greek for helix or spiral.

Pter: Greek for wing, like a pterodactyl.

A hassle is a foreign inclusion in a wool top (what is spun into yarn), which is a real hassle to remove.

A skanky fleece is a wool fleece that is matted and infested with maggots.

The terms date back to the 19rh century.

Either „tea“ or „cha/chai“ exist in some form in virtually every language that has encountered tea, and the distinction between which was adopted generally has to do with whether it was first traded with the country by land (cha) from China or by sea (tea) from Malaysia.

Care means ‘heart’ in french Coeur.

In Russian the days of the week are mostly numbers, e.g. Tuesday is the second day, so Tuesday is Вторник, which comes from второй (second) and the suffix -ник for day. But Monday is not перник as you would expect (первых + ник), instead Monday is Понедельник. This is short for после (after) не (not) делать (doing) -ник (day), i.e the day after not doing anything (Sunday).

In Finnish a tietosanakirja is an encyclopedia, this is a composed word made from tieto (knowledge) and sanakirja (Dictionary). But also sanakirja is a composed word made out from sana (word) and kirja (book). So an encyclopedia is a book of words of knowledge.

‘Bully’ used to mean good friend. There’s a scene in Shakespeare (who else?) where he talks about someone sending his bully boys to teach someone a lesson, meaning he sent his close friends. But, over time, people took it to mean his thuggish friends and so the word’s meaning shifted.

“Son of a gun” is from when sailing ships would come into port. The sex workers would row out to them and have sex with an entire gun crew.

When the kid was born they didn’t know who the father was so he was a “son of a gun” aka a bastard.

Denim= De Nîmes (from the city of Nîmes)

Jeans = Gênes , the French weird for Genoa.

The cotton weave, indigo dyed cloth originated in Genoa, and in France the main production centre was Nîmes.

So ‘denim jeans’ is both a tautology and a contradiction

The term “snorkel” is related to the German word for snoring.

Back in WW2, U-boats (and pretty much all submarines) needed to surface so that they would be able to run their diesel engines in order to charge their batteries because diesel combustion requires oxygen. One German scientist developed a way to get air without having to surface the boat. As this was a very big tactical advantage it was, obviously top secret. In order to not give away what it was, he referred to it by the sound it made i.e. that of someone snoring.

EDITED with new info from helpful Lemmings.

Proto-slavic used the root “dn” (дн) for water, which explains river names such as Dnipro (Дніпро,Днепр), Danube (Дунай/Donau), Don (Дон), Dnjester (Днестр, Дністро).

You might be familiar with the radio term “roger.” Per the FAA’s Pilot/Controller Glossary, it means “I have received all of your last transmission. It should not be used to answer a question requiring a yes or no answer.”

They want to make it VERY clear that roger does not mean “yes.” So why do we use the word “roger” to mean “acknowledged”? Because Americans in World War II.

First of all, radio was still a fairly new warfighting tool in the 1940’s. In a lot of cases, they still used Morse code tapped out by telegraphers on straight keys. Morse code was like the SMS of its day, it takes a long time to spell each letter out, so you end up with abbreviations, some of which really only make sense if you’re familiar with Morse. For example, you know the radio practice of saying “over” and “out?” In morse code, you use K (-.-) to mean “over” and KN (-.- -.) to mean “out.” There’s an entire list of “Q codes”, for example, you can tell someone to reduce their transmitter power by simply transmitting QRP (–.- .-. .–.). There’s one that means “what’s your barometric pressure?” because aviation. You’ll still sometimes hear “What’s QNH?” in aviation circles.

Most relevantly, a reply that simply means “I have received all of your last transmission” is simply abbreviated to R (.-.).

They also had AM voice mode radios. And now we get to talk about phonetic alphabets. We’ve all independently invented one at least once, talking to tech support on the phone and reading a serial number “One Three Four D as in Dog, Two, E as in Egg, Seven Eight one.” Because a bunch of letters sound the same when saying them out loud. You might be familiar with the modern one used by NATO, also required by the aviation world via ICAO. Starts out Alpha Bravo Charlie Delta etc. R in the modern one is Romeo. But NATO formed well after WWII.

The phonetic alphabet used during WWII by English speaking nations went Able Baker Charlie Dog Easy Fox etc etc. Peter Queen Roger Sugar etc etc Xray Yoke Zebra.

So we say “Roger” because in WWII the Morse code abbreviation for “received” was R and the letter R would be pronounced “Roger” on an AM transmitter, and even though the phonetic alphabet has moved on, the word remains in use with a specific definition.

The word “slogan” comes from a swedish word meaning “battle cry”.