One is enough

>>I don't know what's the proper name for this category of words. The cases when one word from a phrase is taken out to mean the whole phrase, despite it having several uses outside of the phrase. For symmetry, I've included a few oddly specific phrases, where an extra word is commonly added to denote the very important difference between the millions of instances of the common variant and the couple of exceptions.

word

is taken to actually mean

why is this wrong

burger

a meat patty of Hamburg recipe, with the bun and toppings; actually, patty is not required, there's a cheese burger

because nobody knows what it is - a Hamburger means "the Hamburgian" - Hamburgian what?

bus

Whoever invented this kind of vehicle, thought it was a good idea to advertise it as "for everybody" and took the latin "omnes" (all, everybody) but in dative case, "omnibus" (to everybody). Then everybody started pronouncing it abbreviated.

calculus

infinitesimal calculus

there are at least several other kinds of calculus - vector, numeric, celestial, difference and plain old calculus (aka arithmetics)

chef

chief cook

The word simply means chief. Saying that chef automatically means a cook is an actual insult to all other chiefs in francophone countries who are not cooks. Like chef de police.

classified

secret, for authorized personnel only

to classify means to split into classes, to assign each peace into a class; this was initially "classified as secret/confidential/sensitive" but was later abbreviated out of context.

commercial

nobody even remembers what it was that was commercial

coup

coup d'etat

because word coup means at least a dozen other things in french

device

anything that is plugged into a computer - disks, printers, floppies.

Made unforgettable by all those "device not ready" messages. The listener has to divine that it doesn't cover any devices not related to the computer (i.e. kitchen utensils, workshop tools etc).

device (2)

portable device

This is newer - it's another computer which is not plugged into the computer on which it's mentioned, but connects to it wirelessly and can be used separately or in connection.

drug

narcotic

it's shorthand for both „pharmaceutical drug“ and „psychoactive drug“, and in many cases it's hard to decide which one was meant.

extension

2nd phone line on the same number

There are also extension cords, fingernail extensions, filename extensions... Actually "phone line extension" was wrong from the start - every phone line is extended from point A to point B, so adding a few meters beyond point B doesn't change its nature and the extension line isn't different from the main line - they are parallel.

flood

lights shining at wide angle, opposite of spotlight

flood is lots of water, "floodlight" is a somewhat poetic description

formula

mother's milk replacement

Formula is a shorthand written expression in maths, physics chemistry. Usually describes a law of nature or a recipe for cooking up a compound. "Baby formula", however, is not a recipe for "how to make a baby".

fries

french fried potato

"Fry" could be anything fried, including electronics, fish, any steak. Besides, it was invented by Belgians.

glass

beaker, tumbler or any other similar vessel

Even when it's not made of glass - it could be plastic.

glasses

spectacles

it's not a plural of glass (as a vessel or as a type of material)

hemi

truck with a hemi (2)

this is a bit recursive...

hemi (2)

engine with a hemi (3)

recursive, I said

hemi (3)

hemispheric combustion chamber

Now roll it back

iron

hot iron

Because the language never bothered to invent a word for this utensil, so it kept the name of the element for it. And it is mostly not made of iron nowadays. Interestingly, many other languages have the word.

iso

a file containing an image of a disk written in ISO 9660 format.

ISO is the international standards organization, not a file extension. Many don't even know this, they say eye ass owe and mean a file.

logout url

post-logout url

i.e. the url to which to go AFTER logout, not the url to go to log out (which usually doesn't really exist, or if it does, doesn't show itself but redirects elsewhere).

military

army

There are thousands of things which are military by nature or origin or by design, but when this adjective is used as a noun (and not as "the military one" like most such adjectives become nouns), then it actually means the army.

musical

musical comedy

Fancy name for an operetta, which probably sounded too posh and foreign for the audience, so it was named "musical comedy", and nowadays after decades of development in its own direction, it's yet another contextless adjective-cum-noun.

oil

the crude mineral oil

because they were too lazy to import some word for it (and it exists in other languages)

oil (2)

painting done with oil colors

mentioning the canvas is optional

pool

pool billiard

word pool has at least two other prominent meanings; to make things worse, many players of pool don't even know the word billiard

promotion

sales promotion

there's also a promotion in any hierarchy, promotion in chess, or simply the act of awarding the title to a graduate

rice pilaf

pilaf

Because, in history, there were a few cases when pilaf was made of wheat. So state million times that this is not the case.

rifle

rifled gun

So the whole gun is called after the helicoidal groove in the bore. Rifle is a gun with rifled bore.

safety

safety lock on a weapon

safety has a dozen other meanings

semi

a truck designed to pull a half-trailer

...Which is not really a half of anything, just doesn't have a front axle. "Semi" is actually a prefix meaning "half".

static

static electricity discharge noise; also any noise disturbing communications

static is anything that isn't moving; this noise only originates in the statically charged things but it is motion by itself.

stereo

stereo sound system

They usually mean the home or car sound system, but there are so many other things which are stereo(-phonic or -scopic), like all 3d movie and/or video systems, binoculars, printed stereographic images... all of them stereo.

sub

submarine sandwich

This is not any kind of sandwich that was invented on, or served on, submarines. The bun resembles a submarine by shape, just as much as it resembles a cucumber or a cigar or a blimp.

tarmac

landing strip for flying vehicles

It used to mean "tar and macadam", the latter being the gravel laid by MacAdam's recipe. It's a precursor to asphalt. The runways are mostly just concrete, so even the mention of tar is misplaced. This is even funnier when SF writers mention tarmac on other planets.

television

television set

Same word is used for television as a system, and sometimes for a television station. That's confusing.

thumb

thumbnail sized image

Thumb is still the part of your hand with which you press the spacebar, not a silly image file.

tissue

tissue paper

now try to wipe your hands with some muscle tissue... or neural

vacuum

vacuum cleaner; clean using vacuum cleaner

Vacuum is utter void, no air, no pressure. Saying "vacuum" to denote some sub-pressure is like calling any fraction a zero. Besides, vacuum is not dirty at all, it needs no cleaning.

vinyl

phonograph record

because it is made of vinyl plastic; to differ from all other items made from same plastic, and from all other types of records made on other media