We could start by attempting to define what a word is, but of course that definition would be made up of words, and I'm sure no one here woke up today intending to disappear into their own navel on a question like this. So we might instead simply note that, of the 26 possible single-letter "words," only three of them have meanings that go beyond tautological references to the letters themselves, or to representations thereof ("I drove my T-top to the Y intersection..."), and decide for ourselves how significant that difference is.
For myself, I would consider "words" that by their nature always fail the use-mention test to be trivial, and probably not worthy of the word word except in certain rather specialized contexts.
I was going through some online articles and I'd like to thank @Josh61 for the right references. I found this detailed write-up on Word Origins from OED by Richard Holden. (I think I now know the reason why top EL&U users strictly stick to OED definitions)
The article: http://public.oed.com/aspects-of-english/word-stories/digital/
What distinguishes digital from many other terms associated with high technology is that it’s not a new word. In the newly revised OED entry, the earliest evidence—in the sense ‘designating a whole number less than ten’—dates from the fifteenth century. OED‘s original entry, published in 1897, does not record this sense. Instead, it covers senses corresponding to another sense of digit, such as: ‘of or pertaining to a finger, or to the fingers or digits’—evidence for which goes back to the seventeenth century. But for most of its history, digital was a relatively unimportant term: it wasn’t until the early to mid-twentieth century that the word became more significant and widespread.
In the late 1930s and early 1940s, the work of mathematicians and engineers led to the development of a new type of computing machine. As opposed to earlier analogue devices, which used a continuous quantity (such as voltage) to compute the desired quantity by analogy, these new machines operated upon data that was represented as a series of discrete digits. For example, in such a system the letter A might be represented as the binary sequence ‘01000001’ (as it is in the ASCII encoding scheme).
Being composed of such sequences of digits, such data (and so any machine making use of it) was hence said to be "digital". Digital computers were generally considered more adaptable and powerful than their analogue counterparts, and digital computing became dominant: the computer you are reading this article on will certainly be a digital one, as will probably any other computer you have ever used. The sense of digital relating to this was covered in OED2 (1989) by the definition, ‘of, pertaining to, or using digits; spec. applied to a computer which operates on data in the form of digital or similar discrete elements.’
Now, to answer your questions...
1. Was Alan Turing aware of the term digital computer? Did he actually ever use it himself?
Yes. Alan Turing developed the Turing test, and uses the term often in his seminal paper "Computer Machinery and Intelligence".
"Are there imaginable digital computers which would do well in the imitation game?
[Wikipedia]
2. Could one describe the British Bombe as being a digital computer? Wikipedia calls it an “electromechanical device”
I would say No. At least not a "digital computer". It's called electromechanical because it operated on electricity and had rotors, wires and plugboards that carried out the deciphering work. Importantly it did not operate on 0s and 1s, which is the definition of a "digital computer".
(noun). an electronic computer in which the input is discrete rather than continuous, consisting of combinations of numbers, letters, and other characters written in an appropriate programming language and represented internally in binary notation
[Collins Dictionary]
The ENIAC is widely believed to be the first ever "digital" computing device.
It was Turing-complete, digital, and could solve "a large class of numerical problems" through reprogramming
[Wikipedia]
You could probably say it was an "analog computer"!
(noun) a mechanical, electrical, or electronic computer that performs arithmetical operations by using some variable physical quantity, such as mechanical movement or voltage, to represent numbers
[Collins Dictionary]
3. When was the term digital computer actually coined?
The exact time and person who coined it remains a mystery. Etymonline suggests that both "digital" and "computer" originated in the middle of 16th century but the combined term, i.e., "a digital computer" might have its origins at the beginning of the 20th century, and a spike in usage by late 1940s, according to Ngrams.
Best Answer
The distinction you are making is not inherently necessary. It depends on the game in question. Here are some basic terms and how they would apply:
"Solitaire" has been adapted for usage in board games that allow one player to play on their own but is still technically considered exclusive to card games. It is really only used for "puzzle" or "challenge" style games where you are trying to accomplish a particular goal based on a set of rules (i.e., the game). It would not be remotely appropriate for running through an FPS on your own just to learn the details of the map.
There is no suitable distinction between a single-player game that refers to competing against AI versus a single-player game similar to solitaire. Multiplayer is merely the opposite of single-player:
Which brings us to the definitions of various players:
Most players are human players but it is technically correct to refer to any active, independent competitor as an "AI" or "computer" player. The key distinction between an AI "player" and just some "AI" built into the game for the purposes of challenge is whether the participant fulfills the same role as a human player would.
What this means for the terms of single-player and multiplayer is that the game can be designed to support built single-player and multiplayer modes (see above) and those player seats can be filled by human or computer players.
Typically, however, the menu options in games need to distinguish between a game full of human opponents and a game against AI opponents. This terminology is very game specific and although the industry has some conventions there is no technically correct way to label things. The conventions I see most often:
To directly answer your question:
This is referred to as single-player or solitaire, depending on the content of the game.
This is referred to as single-player or practice or multiplayer depending on how the game was started. If it is a unique game mode that is completely seperate from the normal multiplayer mode and you have a standard singleplayer mode then you will need a term similar to "practice mode".
If "practice" is unsuitable you could use any of the following:
The best term for this is multiplayer. Other terms for it exist but are only really used when more than one multiplayer mode needs to be distinguished.