English still uses middle for a location, a span of time, a rank, and a part of the body. As an adjective it marks what sits equally far from two extremes, or what is merely intermediate rather than central. As a noun it names that place: the middle of a street, a book, a night. It is also the waist, the second item in a set of three, and, in politics, the unaligned stretch between camps. Those uses look modern because they keep attracting new compounds. The simplex itself is old.
Inherited, not imported
The origin of the word middle is Germanic inheritance, not a French or Latin loan. Old English already had middel as adjective and as noun. The adjective meant equally distant from limits, or intermediate. The noun meant the point or part so placed, and, already in that period, the middle of the human body. Middle English carried the same word forward as middel, myddel, and several other spellings. Modern middle is that native line with a later spelling, not a replacement from abroad.
Dictionaries that publish dates put first English use in the Old English period, before the twelfth century. The word was in the language before 1066. That matters because so many English abstracts did arrive from French after the Conquest. This one did not. It belongs with the everyday native stock that never needed to be borrowed.
Close West Germanic kin make the inheritance obvious. Old Frisian middel, Old Saxon middil, and Old High German mittil are the same formation. Dutch middel and German mittel, with the noun Mittel, are still in daily use. English also kept the shorter sibling mid, from Old English midd. Middle is not a different idea from mid; it is the same stem with more of its old morphology still attached.
A diminutive that stopped sounding small
Comparative Germanic work treats the longer form as a diminutive. Proto-Germanic had the adjective *midjaz and a noun *midjō. From that stem came *midlą, *midilą, or *medalą, built with the suffix *-il-. Proto-West Germanic *midla- is the immediate source of Old English middel. English later lost any sense that the suffix made the word a little mid. The extra syllable remained as ordinary bulk, which is why the modern word does not feel diminutive at all.
The deeper root is Proto-Indo-European *médʰyos, also written *medhyo-, meaning between or in the middle. Handbooks agree on that step. A further tie to a root *me- meaning to measure is sometimes suggested and remains uncertain; it is safer to stop at *médʰyos.
That Indo-European adjective is widely reflected. Latin medius, Greek mesos, Sanskrit madhya-, Avestan madiya-, Gothic midjis, and Old Church Slavonic medzu, meaning between, are independent descendants. They are not sources of the English word. Latin later sent English a second wave of the same family through Romance: medium, median, mediate, medieval, Mediterranean. Those sit beside native mid and middle as reborrowed cousins, which is why English can say both middle and medium without either being a corruption of the other.
The short native stem kept working in compounds while the longer form became the ordinary free word. Old English midhrif, later midriff, joins mid to hrif, belly. Midst is mid with an adverbial ending; amid goes back to a phrase on middan that later behaved like a preposition. The language did not choose between mid and middle. It kept both and specialized them.
Geometry that kept finding new objects
The spatial core has barely moved: a point or stretch equally far from the edges. Old English already applied the noun to the waist. From about 1300 it is also recorded for the second of three, the same geometry applied to a series rather than a line. Around 1200, middle way is already a figurative path of moderation. Middle-sized is in use by the 1620s. Late Old English called the third finger, thumb counted first, the middle finger.
Later English kept filling the same slot. Middle management, by 1941, is the layer under senior staff. Middle ground, by 1961, is a compromise between extremes. Middle-of-the-road, from 1894, begins in politics. One explanation notes that a dirt road's edges wash out; a likelier image is the middle as the line less open to ambush.
A few compounds drifted farther from plain location. Middle school is attested from 1838 as a school for middle-class children; only about 1960 did it come to mean the grades between elementary and high school in American usage. In early United States geography the Middle States, from 1784, were New York, New Jersey, Pennsylvania, and Delaware, the band between New England and the South. Middle America for a conservative middle class treated as one bloc dates from 1968.
Dutch and German split from English on another sense. Their middel and Mittel also came to mean means, method, and medicine. English kept middle for place and used other words for instrument and remedy. An obsolete English verb to middle once meant to take a middle view, in the seventeenth and eighteenth centuries, and later, at sea, to fold a rope in half. Those verbs faded. The adjective and noun did not. Grammar later reused the adjective for the middle voice, in which a subject both acts and is affected. That is a technical overlay, not an Old English meaning.
What the extra syllable still shows
English did not have to borrow a word for the center. It inherited two: short mid and suffixed middle. When the noun names a waist, that sense is already Old English, not a later slang for the torso. The same Indo-European adjective that produced Latin medius and Greek mesos produced, through West Germanic, a word that never left the language. The extra syllable is an old diminutive suffix that English stopped hearing as small, and that is why mid and middle still stand side by side.