Retronym

A retronym is a new word or phrase coined for an old object or concept whose original name became used for something else, or was no longer unique. "Retronym" is a neologism coined by Frank Mankiewicz [1] and popularized by William Safire [2] in 1980 in the New York Times. A lot of these are created by advances in technology. Some examples:

Analog watch: Before the advent of the digital watch, all watches had faces and hands. After the advent of the digital watch, watches with faces and hands became known as analog watches.
Black-and-white television: Once called simply television, now the retronym is used to distinguish it from color television, which is now more commonly referred to by the unadorned term. Along the same lines: broadcast television, silent movie.
Brick-and-mortar store: A store with a building that customers can visit to examine its goods (which others might purchase at an online store).
Cold water faucet: Before the invention of the hot water heater, there was only the single faucet/tap at each sink.
Day baseball: Baseball played during the day, as all games were played before electric lighting in stadiums became common.
Desktop computer: Until portable, laptop, and notebook computers became popular, computers that fit on a desktop were often referred to as home computers or personal computers.
Face-to-face conference: A conference, not involving telephones or video cameras (similarly:IRL-meeting = in-real-life meeting).
Forward slash: Before the rise of Microsoft's MS-DOS computer operating system, with its frequent use of the backslash ("\") character in extended file names, the symbol "/" was known simply as a "slash" (also oblique or solidus). Calling it a "forward slash" became a useful expedient for distinguishing the two symbols.
French franc: The currency unit of France before the euro, which was originally the only franc, but had to be distinguished from the Belgian franc, Communauté Financière Africaine franc, and Swiss franc after those countries adopted it.
Hard cider: In Eurasia, "cider" refers to fermented (alcoholic) apple juice. In the US, cider often refers to non-alcoholic tangy or carbonated apple juice. "Hard cider" specifies the alcoholic version.
Hard disk: All disks were hard (i.e., constructed of rigid instead of flexible magnetic material) until the floppy came along.
Hot chocolate: In the days before the invention of sweet solid chocolate for eating, the word "chocolate" was usually used to refer to the drink; references to it in, say, Jane Austen's novels are confusing to the 21st century eye. For a while after the chocolate bar was invented it was referred to as "bar chocolate", but due to its stunning rise in popularity in the latter half of the 19th century it eventually laid claim to the basic word.
Landline phone service: With the advent of celluar phone service, traditional hard-wired phone service became known as landline phones. Even though a considerable amount of landline phone traffic is transmitted via airwaves, this term comes from the physical cabling that provides the "last mile" connection between the customer premeses and local phone distribution centers.
Latin America, Anglo-America: Since the term America tends to be associated (however controversially) with the United States of America, Latin America provides more precise identification of the largely Spanish- and Portuguese-speaking countries in the Americas. Likewise, the remaining, primarily English-speaking countries of the USA and Canada are sometimes referred to as Anglo-America.
Live poker: What casinos call the kind of poker played with cards by people sitting at a table; what many others still just call "poker"; also called a "ring game". The term became necessary to distinguish it from video poker, which is far more common in casinos today.
Mainframe computer: When minicomputers (which were the size and shape of a desk or credenza) were introduced in the early 1970s, existing systems that often consisted of multiple large racks of equipment received the portmanteau "mainframe", alluding to the vertical cabinets or "frames" in which they were installed.
Manual transmission: They were all manual, of course, before the invention of the automatic transmission.
Meatspace: All of physical reality, as distinguished from cyberspace.
Natural language: A language, used by humans, that evolved naturally in its society. Contrast with computer programming languages or constructed languages.
Paper copy: With the proliferation of insubstantial and indistinguishable digital document copies, physical document copies acquired this retronym. Occasionally extended to the copying devices; i.e., paper copiers. The jocular substitute dead-tree copy is sometimes used. NOTE: The synonym hardcopy predates the digital age, apparently differentiating paper copies from microfilm and other human-unreadable forms.
Prop airplane: As jet aircraft became the primary people movers of the airways, the older propeller-based technology received this occasional shorthand nickname to distinguish it.
Rotary telephone: The kind of telephone in common use before touch-tone telephones.
Pocket watch: Before the advent of the wristwatch, the word "watch" referred to watches carried in the pocket. After the advent of the wristwatch, the word watch referred to a watch worn on the wrist.
Reel-to-reel or open reel tape recorders were originally simply tape recorders, as they all used a pair of open reels to hold the magnetic recording medium. The term reel-to-reel was introduced when various forms of cassette tape formats became popular.
Sit-down restaurant: With the rise of fast-food and take-out restaurants, the "standard" restaurant received a new name.
Snail mail (AKA land mail, paper mail, p-mail): Non-electronic mail delivered to physical locations, like one's home or business. Before email and vmail, all mail was physical.
Vinyl record: A term that arose to distinguish 33⅓- and 45-rpm analog disc records (LPs and 45s) from the compact discs (CDs) that have since replaced them for nearly all physical record albums.

Some retronymic adjectives include:

Acoustic: Describes non-electric ("unplugged") musical instruments that do not require an amplifier: acoustic guitar, acoustic piano.
Analog: Describes non-digital devices: analog clock, analog recording, analogue disc record.
Conventional or traditional : Describes devices or methods that have been largely replaced or significantly supplemented by new ones. For example, conventional (non-microwave) oven.
I, Sr.: When a child or a dynastic ruler receives a name identical to his or her predecessor, the original is often retroactively given the suffix Sr. (for family names) or the Roman numeral I (for dynasties and for three or more generations of families). Examples:
- William I of Orange was called William during his lifetime.
- Country singer Hank Williams became known as Hank Williams, Sr. when his son Randall Hank Williams adopted the stage name Hank Williams, Jr..
- Note: Sr. (senior) and Jr. (junior) are usually used only for males.

Compare to backronym