Blocking first, standing still later
In present-day English, stop can mean to cease moving or acting, or to prevent something else from going on. The same spelling also names a pause, a station, a traffic command, a punctuation mark, and a class of consonants. Those later uses rest on an older physical picture: not a person standing still, but a hole being filled so that nothing can pass.
That picture is the origin of the word stop. A West Germanic verb for plugging a passage grew, in English, into the ordinary word for coming to a halt.
From Old English into Middle English
The modern verb comes from Middle English stoppen. Behind it stands Old English -stoppian, clearest in the compound forstoppian, to stop up or stifle. The simple stem is poorly attested in the earliest records, so dictionaries reconstruct it from the compound and from later Middle English.
Dates for the unprefixed verb do not match across references. The Oxford English Dictionary places the earliest evidence around 1225, in the Ancrene Riwle. Other desk dictionaries, counting later well-documented senses, give a fourteenth-century first date. Either way, the word is already English in the medieval period, not a late French loan that arrived as a finished synonym of halt.
Early uses stay close to matter and apertures. A passage could be obstructed with a barrier; an opening could be closed by stuffing or plugging. By the early fourteenth century the verb is used of the ears. By the late fourteenth it can hinder a person or a process, and the related noun appears as a plug. Around 1400 it can mean to shut someone in, and also to prevent an action from continuing.
A West Germanic set with a disputed parent
English did not invent the plugging verb alone. It belongs with Old Saxon stuppon, West Frisian stopje, Middle Low German stoppen, Old High German stopfon, German stopfen (to plug or stop up), and Old Low Frankish (be)stuppon (to stop the ears). Dutch stoppen belongs here too, and from Low German or Dutch the type later reached Swedish stoppa and Danish stoppe.
One long-standard account treats Proto-West Germanic stoppōn as a borrowing of Vulgar Latin stuppāre, to stop or stuff with tow or oakum. That Romance verb would come from Latin stuppa, the coarse part of flax, itself from Greek stúppē with the same meaning. Italian stoppare and French étouper continue the Latin line. Plugs of tow were used in the Rhine valley from antiquity, which is the usual argument for early contact. American Heritage and Merriam-Webster still present this path, usually with a hedge such as probably.
A second account, associated with Barnhart and now favored in several Germanic reconstructions, treats the whole group as native. On that view the verb goes back to a Germanic base of the stoppon type, perhaps related to verbs meaning to push, pierce, or prick, and further to an Indo-European root for striking or thrusting. The Oxford English Dictionary now classifies English stop as inherited from Germanic rather than as a Latin loan.
The objection to the Latin story is semantic. The earliest Germanic uses do not mean stuff with tow. That fiber-stuffing sense looks later, as if similar-sounding Romance words had colored a verb that already meant to close or block. The Century Dictionary had already called the Latin derivation phonetically plausible but doubtful on grounds of meaning. English inherited a West Germanic verb for closing an opening; whether it began as a Rhine-valley Latin borrowing or as a native Germanic formation is not settled.
One related legal word should not be treated as a French source of the English verb. Anglo-French estopper, the ancestor of English estop, is generally taken as adopted from the English verb, not as a variant of Old French estouper that later became stop.
How a plug became a halt
The senses that dominate speech today — bring or come to a halt, discontinue a course of action — are a later English development of the fifteenth century. They grow from the older idea of preventing a flow by blocking a hole. Stop a pipe, and the water no longer moves. Extend that image from liquid to people, clocks, speech, and plans, and you have the modern verb.
The timeline of that extension is fairly clear even where the ultimate root is not. Late fourteenth century: hinder from progress. About 1400: prevent continuance. Mid fifteenth century: cessation as a noun. 1520s: leave off, and, intransitively, cease from forward motion. By 1711, of travelers, make a halt or stay. By 1733, of abstract things, come to an end.
The later export is clear. The halt meaning is a specially English growth. Other Germanic languages kept their older plugging verbs; German stopfen still means to stuff or darn. Then, in marine and railway language, English stop was borrowed back out: French stopper, and halt uses of German and Dutch stoppen. A native-looking European verb for halt is, in that modern sense, often an English loan.
What the noun kept
The noun tracks the verb. Late fourteenth century: a plug. Mid fifteenth: a cessation. About 1500 it names the device on a wind instrument that closes a hole and changes the tone, and then, on the organ, a rank of pipes and the knob that brings them in. Opening more ranks swells the sound; the later idiom pull out the stops, recorded from 1909, still uses that mechanism as a figure for making every effort.
Other specialized nouns show the same core. By the 1560s, a pause in speaking; by the 1590s, a mark that signals such a pause in writing. A full stop is the end of a sentence, later shortened in telegram style. From the 1660s, phoneticians call a consonant a stop when the vocal tract is closed completely. A stopping place as a named location is nineteenth-century. The traffic stop-sign is recorded from 1918.
Each is the old plugging verb applied to a new kind of closure: of air in a pipe, of a clause, of the mouth, of a road.
If one fact should stay after the dates fade, it is this: English did not borrow its everyday halt-verb from French stopper. The borrowing ran the other way. What English first possessed was a West Germanic word for filling an opening. Only after that word had learned, in English, to mean stand still did neighboring languages take the newer sense back. The disputed Latin tow-plug remains an open question at the root; the traffic sign is late, local, and clearly English.