What speakers mean by it now
In ordinary English a mark is a visible trace: a stain, a scratch, a tick on a list, a stamp of quality. It is also a target, a score on a test, a version number on a machine, and, in slang, the person a fraud is aimed at. Those uses look scattered until they are set against one older idea: a line that shows where one thing ends and another begins.
The verb keeps the same range. To mark land is still, in some legal and surveying language, to fix its bounds. To mark a page is to leave a sign on it. To mark an essay is to grade it. To mark someone’s words is only to notice them.
A native word, not a French import
The noun is inherited. Old English had mearc in the West Saxon dialect and merc in Mercian. Already in that period the word covered both a boundary and a sign that stood for one: a limit, a landmark, a defined district. The verb was already there too. West Saxon mearcian and Anglian merciga first meant to trace out bounds; still in Old English they also meant to put a sign on something. Middle English kept mark, merk, and merke. Standard dictionaries date both noun and verb to before the twelfth century.
This is not the French-looking cousin march, the border territory. That English march comes from Old French marche, itself a Germanic loan. Old English mearc would not have yielded the ch spelling. The two words are relatives that entered the language by different routes.
Etymologists do not all describe Scandinavian contact in the same way. Some treatments present Modern English mark as a straight descendant of the Old English noun. Others, including the Oxford English Dictionary, call it of mixed origin: native mearc plus influence from, or partial borrowing of, early Scandinavian forms such as Old Norse merki, a boundary or sign. Old Norse also had mörk for a forest, often the woodland that served as a frontier. The overlap in form and sense makes a northern contribution plausible. How large that contribution was is harder to weigh.
The older root
Behind the Old English forms stand reconstructed Proto-West Germanic marku and Proto-Germanic markō, both in the region of meaning “boundary” or “boundary marker.” Those are traced to a Proto-Indo-European noun mórǵs, “edge, border,” from a root often given as merg-. A further step that would link that root to a verb meaning “to divide” is sometimes offered; it remains uncertain, and the article does not depend on it.
The family is easy to see across Germanic. Gothic marka is a frontier. Old High German marha or marca is a boundary. Dutch merk is a brand or identifying stamp. German Mark still names a borderland, as in the historical marches east of the Elbe, while Marke is a brand or token. Swedish mark is land or ground. Latin margo, “edge, margin,” is a cousin rather than a parent. So are Welsh bro “district,” Old Irish mruig “borderland,” and Persian marz “frontier.”
Germanic speakers lent the word into Romance early. From French marche come English march in the border sense, and marquis and marchioness as titles of the lord of such a march. Denmark is the Danes’ mark, their borderland. The name of the kingdom of Mercia is related: it sat on a frontier of the early English kingdoms. English remark is later still, from French remarquer, built on the same Germanic stock rather than invented inside English.
The verb’s Germanic relatives keep the mental shade. German merken means to notice. Old Saxon markon could mean to appoint or observe. The English verb that now covers staining, grading, and paying attention is one old action—setting a bound—stretched across objects, paper, and attention.
How the senses spread
By Old English the path from boundary to sign was already underway. A post or stone that stood for a limit became a sign in general, then any impression left as a sign. The sense “any visible trace” is recorded around 1200. Late Old English already used the word for the cross an illiterate person made in place of a written name. From the thirteenth century it is a target to shoot at. From the fourteenth it is a guide-stone for travellers and a point on a measuring scale, including the bits of leather or bunting on a sounding line. From the fifteenth it can name a particular design or make of an object, the ancestor of later Mark I and Mark II on machines. Attention and importance—a person of mark, a matter worthy of mark—belong to the early modern period.
Later specializations sit on that same line. The starting line of a race is attested by 1887; the starter’s call on your marks by 1890. Academic scores in the Commonwealth sense are nineteenth-century. The slang mark, a gullible victim of a swindle, appears in the eighteenth: the person aimed at, as an archer’s target had been centuries earlier.
A second word that looks the same
English also had, from late Old English, marc: a unit of weight, chiefly for gold or silver, of about eight ounces. In England it became a unit of account equal to thirteen shillings and fourpence, two-thirds of a pound sterling, and was used that way into the eighteenth century. It was never, in England, the name of a circulating coin. Merriam-Webster and the Middle English Dictionary treat this marc as probably from Old Norse mörk, perhaps introduced with Scandinavian settlement. It is related to German Mark, later the German currency; a silver mark of the new German empire was issued in the 1870s.
Whether that money-word is simply the sign-word applied to a stamped bar of metal is disputed. Some etymological dictionaries of German call the connection unproved, because the term first denoted a fixed weight, not a stamped coin. The link is therefore likely but not settled. The personal name Mark, from Latin Marcus, is a different word that happens to match in modern spelling.
Keep the old boundary post in mind and the origin of the word mark is no longer a scatter of unrelated meanings. Almost every later sense—scratch, target, grade, starting line, even the person a con is aimed at—is that post after it stopped being a fence and became whatever people aimed at, measured from, or used to tell one thing from another.