I tried searching for things like opposite of solid-state, but most of what I've found suggest things like liquid-state. I'm pretty sure a drive that is not solid-state contains no liquid to speak of.
Is there a one word antonym for the use of solid-state in this context?
Solid-state drives are called solid-state because there are no moving parts in them. Drives with moving parts are called hard disk drives, because they contain disks which rotate when the drive is powered on. You could consider this an antonym, but not necessarily. They are simply two different technologies, with many other possible to come.
The word you are looking for is "magnetic" or "mechanical" (i.e. a mechanical disk drive).
The word "disk drive" has become very ubiquitous and a layman is likely to apply the term to other storage technologies. So, while technically you would be correct in saying that a disk drive is something that is not (technically) "solid-state", the term could easily be confused.
This is an English/communication question; not a technical one. The only way to guarantee understanding is to properly describe the specific technology you are referring to — mechanical disk drive, platter-based disk drive, old-style noisy rotating spinny magnetic planar disks with crashing heads inducing much rage systems — don't get too caught up in the technical accuracy when communication and understanding are important.
I'd quibble with some of Rimmer's definitions, but his point is essentially correct.
I believe the real definition of solid state is something more like "made with transistors and/or integrated circuits". An old vacuum tube memory unit has no moving parts, either, but wouldn't be called solid state. Core memory had no moving parts, etc. (I don't mean to be critical; I'm sure someone could quibble with my definitions too. Just trying to clarify.)
Hard disk refers to a technology where data is stored on spinning, rigid disks. We call it hard to distinguish it from floppy disk, where the disks are flexible, and disk to distinguish it from drum storage, where data was stored on the outside of a cylindrical device, i.e. a device that was drum-shaped. (Drum drives have been obsolete for a long time and floppy disks are just about gone, I think.)
A CD is technically a disk that is hard, but we don't call it a hard disk because the technology is quite different and we need to distinguish.
Yes, by definition a hard disk drive is not solid state, just like by definition a cathode-ray tube is not a liquid crystal display, etc. I suppose you could make a disk-shaped solid state memory device, but we wouldn't call it a hard disk drive except as a joke.
Personally I think calling a solid state memory unit a drive is a misnomer, as I understand the word drive to refer to a device with a motor that spins something. But solid-state drives have picked up that name by analogy, I think; they're like a hard disk drive except that they're solid state.
And to ditto Rimmer, they're not really opposites; they are two of many existing and many more possible technologies. I've mentioned seven in this post: core memory, vacuum tubes, drums, hard disks, floppy disks, solid state, and CD. I'm sure in the future we'll see other technologies.
The typical acronyms and phrases are HDD for Hard Disk Drive and SSD for Solid State Drive.
The generic "parent" term is DD for Disk Drive.
Adding to this list is FDD for Floppy Disk Drive (remember those?), ODD for Optical Disk Drive (more common terms are CD, DVD & Blu-ray Drives though), Tape Drive and USB Flash Drive.
To answer your question though, there really is no opposite term, since hard disks aren't binary in their nature (yes pun intended)
Disk Drive (DD) is the common usage.
Solid-state does not really have an opposite when it comes to this tech. Solid-state in this case refers to the quality of the hard drive; that it does not have moving parts and its internal memory storage is (simply) a solid, non-moving material. A standard hard drive has plates (disks) and arms that move and is, or at least was, called a "hard disk drive".
The headline question, What do you call a disk drive that is not solid state?, actually reveals the answer, and also the confusion. The storage device that a solid-state drive (SSD) replaces is called a disk drive.
The confusion comes because, on the time scale of language evolution, the technology is new and the wording hasn't completely settled down. The original name for a disk drive was magnetic disk drive (which was equipment that rotated a magnetic disk), but because essentially all disks in the computer context were magnetic, the magnetic was dropped. When consumer PCs appeared, they first used only floppy disks (so called because the magnetic disks were flexible instead of the conventional rigid, or hard, disks). Then consumer PCs got higher-performing hard disk drives, which were usually called hard drives or hard disks to distinguish them from the earlier consumer disk drives which were used for floppies.
When the flash-memory-based replacements for hard disk drives appeared, they came to be called solid-state drives, which showed their function as similar to that of a disk drive, and their distinct nature, solid-state. There is no disk inside a solid-state drive, just integrated circuits (chips). The term solid-state dates way back to vacuum tube (British: valve) days, before transistors or chips. When invented, transistors (and similar things, like later chips) were called solid-state devices from the physics term solid which distinguished them from earlier devices using a vacuum. So solid-state was used for things built out of chips (like solid-state memory such as RAM), and so was used for the non-disk hard drive replacement, the solid-state drive.
Exactly what "opposite" means in the context is a little hazy, but it might be reasonable to say in the context of mass storage drives there are solid-state drives and disk drives (which could include optical disk drives as well as hard disk drives).
Most non-SSDs could accurately be called a "spinning disk drive".
I know this isn't a long answer like the others, but you might also consider Magnetic Storage. Magnetic Disk Drive would work as well.
Hard Disk Drive (HDD) is typically used as the generic for non Solid State Drives (SSD).
Alternative "disk drives" include:
Usually just be specific, rather than looking for an all-encompassing word, but usually it depends on context and why you're trying to differentiate.
Since the most common alternatives to solid-state drives are "hard disk drives" and "floppy disk drives", a common term to refer to non-SSD disks is "spinning media."
The simple answer to your question is Non Solid State Drive
Why? Because Solid state drives are one family and there are others out there: Optical, Magnetic disk and tape drives to name a few. So it would be incorrect to say that Hard Disk drives are the opposite of Solid State drives.
Now if you are meaning to ask for the most common alternatives to Solid State drives, its probably Hard Disk Drives or optical media (cd/dvd/blue ray) which are alternatives to Solid State drives (depending on application)
I use the term mechanical or electro-mechanical drive.
