A pause in ordinary seeing
English uses wonder for both a feeling and the object that causes it. The noun can mean awe, surprise, or a curious halt in front of something that does not fit the usual account of the world. It can also mean the marvel itself: a feat, a prodigy, a person of startling skill. The verb still allows astonishment, but everyday speech more often uses it for speculation and unanswered questions. To say I wonder why is not a report of rapture; it is a request for an explanation that has not yet arrived. An attributive use, as in wonder drug, treats the word as a marker of the extraordinary.
Those senses sit close together in modern usage, which can hide how they arrived at different times. The feeling, the spectacle, the puzzle, and the polite question are not equally old.
Native English, not a loan
The origin of the word wonder is native. It did not arrive with Norman French, and it is not a later learned borrowing from Latin. Old English already had the noun wundor for a strange or marvelous thing, an event that seemed to stand outside ordinary experience, and an object of astonishment. The matching verb was wundrian: to be struck with amazement, to admire, and even to make something appear wonderful. Both are recorded in the Old English period, before the twelfth century.
Middle English kept the pair. The noun appears as wonder and wunder; the verb as wondren and related spellings. Modern English continues that line rather than replacing it. Historical dictionaries that treat the noun as inherited from Germanic, and that set Old English wundor beside Old High German wuntar, are describing the same fact: English received the word from its own West Germanic parent, not from a neighbor after the language was already English.
A Germanic family
Behind Old English sits a reconstructed Proto-West Germanic noun, and behind that a Proto-Germanic neuter usually cited as wundran or wundram, a marvel or miracle. The family is still easy to hear. Dutch has wonder. German has Wunder. West Frisian has wonder and a rounded variant. Old Saxon had wundar. Low German keeps related shapes. Scots keeps a native form in wunner.
North Germanic shows the same stem after a regular change: Old Norse dropped the initial w and gives undr, continued in Icelandic undur and, in the sense of a miracle, in Danish, Norwegian, and Swedish under.
The verb is equally old in the family. Proto-Germanic had a derived verb meaning to wonder at, continued as Old English wundrian, Dutch wonderen, German wundern, and Swedish undra. English did not coin the verb from the noun in the modern period. It inherited both the thing and the act of being struck by it.
Further back the trail splits. Several standard etymological references stop at Germanic and call the deeper source unknown. Other reconstructions, including a proposal in a 2003 handbook of Germanic etymology that some open dictionaries follow, attach the noun to a Proto-Indo-European root for desiring, wishing, striving, or loving, with a suffix of the kind that can form a thing associated with that action. If that account is right, English wonder would sit at a distance from wish, and more loosely from a set of words that includes Latin Venus. The jump from desire to marvel is not obvious, and the link is not agreed. The Germanic stage is secure. The Indo-European stage is a hypothesis.
The thing came first
The earliest English uses treat wonder as something in the world: a miracle, a portent, a sight or event that could not be folded into the ordinary. Late Old English already stretches that toward a puzzle, a cause of perplexity. Only in the later thirteenth century does the noun become common for the inner state itself, the amazement or reverential awe that novelty can excite when the cause is not well understood. By the middle of the fourteenth century it can also mean a spectacle.
That order matters. English did not start with a name for a private emotion and later apply it to miracles. It started with the marvel and later named the feeling the marvel produces. Using one word for both is a Middle English development, not the original design.
The verb moved on a parallel track. Astonishment is the older core. By late Old English the verb can also mean to be puzzled, to entertain doubt, to speculate with interest. That is the ancestor of the modern I wonder, which often means I should like to know rather than I am thunderstruck. Curiosity grew out of perplexity; perplexity grew out of being confronted with something that would not explain itself.
Middle English also used a reflexive pattern, I wonder me, still reported in parts of Yorkshire and Lincolnshire. A related impersonal construction, it wonders me, is attested from the sixteenth century and survives in some Pennsylvania German English, modeled on German. Those constructions keep an older idea that wonder is something that happens to a person, not only something a person does with a question.
Set phrases show how early the word settled into ordinary talk. A late Old English way of saying that something is unsurprising already uses the noun with a negative. The proverb that a novelty holds the public for nine days is medieval. The set phrase nine days' wonder is later, from the 1590s, with a Chaucerian nine-nights version behind it. None of these require a new etymology. They are the inherited noun doing social work: naming what startles, and then naming how briefly the startling thing holds attention.
The older sense did not collapse. English still uses the word for miracles and marvels, for translated lists of ancient monuments, and for a person or product sold as exceptional. The curiosity sense of the verb grew beside the marvel sense of the noun. It did not erase it.
The consonant English kept
A compact way to hear the history is to set English beside its northern cousins. Old Norse undr is the same Germanic word after the loss of w at the beginning of the stem. English never made that change. German Wunder and Dutch wonder kept the consonant too. One inherited marvel-word, split by a regular northern sound change, still names astonishment on both sides of the North Sea. The form with w is not a later flourish. It is the older shape, preserved.