Not dead, and usually not in front of the noun
In current English, alive names the condition of having life. A person, an animal, a plant, even a hope can be described that way. The core contrast is with dead or extinct. Around that core sit several ordinary extensions: a debate that is still in play, a room swarming with voices, a mind that is alive to a danger, wiring that carries current.
Grammatically the word is fussy. Native speakers say the fish is alive far more readily than an alive fish. Attributive slots go to living or to live. That is not a modern style rule. It is leftover syntax from a prepositional phrase that never fully became a free-standing adjective.
From on līfe to one word
English did not import alive from French or Latin. It inherited a two-word Old English locution, on līfe, meaning in life or in the living body. On is the old preposition in the sense in or on. Līfe is the dative singular of līf, the native noun for life. To be on līfe was to stand in the condition of living.
Middle English keeps the trail in spelling. Scribes wrote on live, on life, alife, alyve, olive, olife, and at last alive. The origin of the word alive is that contraction, not a newly coined root. References that date the adjective around 1200 are marking the fused form. Others that say before the twelfth century are counting the Old English phrase itself. Both are tracking the same native material. The uncontracted on live was still in use in the seventeenth century, so the one-word spelling did not instantly erase the older phrase.
The first syllable is the reduced a- of asleep, abroad, afoot, and ashore: Old English on in an unstressed position, forming adjectives and adverbs with the sense in or at. Some modern dictionaries analyze the later spelling as a- plus live in the meaning life. Accounts that stay closer to Old English morphology keep the dative of līf in view. The disagreement is about how to slice the fused word, not about where it came from.
What it replaced
Old English already had cwic, living, the source of modern quick. Alive did not appear because English lacked a word for not dead. Over time the fused phrase took the central job, and quick narrowed. It remains in the quick and the dead, in quicklime and quicksilver, and in the older sense of living flesh. Those survivals show the earlier adjective, not a later story about speed.
The later adjective live, as in live animals or a live broadcast, is a shortening of alive from the 1540s, with the unstressed a- dropped. Once clipped, it could sit in front of a noun. Alive kept the predicative habit of the original phrase. The two forms still share work: live ammunition and an alive wire are the same metaphor of unspent energy, split by syntax.
Stick, remain, live
Inside the phrase sits a Germanic noun. Old English līf is related to Old Norse lif, Old Frisian and Old Saxon lif, Dutch lijf, Old High German lib, and German Leib. Several of those cousins mean body as readily as life, a reminder that the Germanic idea was corporeal continuance rather than an abstract vital spark. The associated verb is Old English libban in West Saxon and lifian in Anglian, from a Proto-Germanic stem reconstructed along the lines of a form meaning to remain in life. Old Norse lifa could mean to be left as well as to live, which fits a family of remaining rather than a family of breath and soul.
Many handbooks then point to a reconstructed Proto-Indo-European root meaning to stick or adhere, a root that also yielded words for continuing. The path from stick to remain to live is semantically tidy, but it is mainly a Germanic development, and specialists have treated that last jump as less than certain. What can be said without leaning on the reconstruction is simpler: English life, live, and alive belong to a native Germanic set, not to Latin vita or Greek bios.
Sister languages still use the syntax English fused. Dutch has in leven, German am Leben, Norwegian i live, Icelandic á lífi. Each is a preposition plus a life-word. English did that work early and then hid the preposition in a reduced first syllable.
Meanings that grew out of continuance
The literal sense, in life, never receded. Around 1600 the word was applied to abstractions that had not been extinguished: affection, litigation, a flame kept going. By 1709 it could mean active or lively. By 1732, usually with to, it meant attentive or receptive. A street alive with traffic is not merely undead; it is full of motion. Electrical English later applied the same image to a conductor that carries current.
Emphatic patterns followed. No man alive raises a claim to the limit of the living. The vocative man alive is recorded from 1845. Alive and kicking, vigorous rather than merely breathing, appears from 1823. One later gloss linked kicking to a child in the womb after quickening; kicking as lively is attested earlier, in the sixteenth century. Either way, the idiom keeps the old association of life with movement.
Because the word began as a location, it still prefers to tell you where something stands: in life, in force, in motion, in awareness. That residue is grammatical, not decorative.
The leftover preposition
The useful detail is small and physical. The a- of alive is not a Greek negative and not a Latin toward. It is the same worn on that puts a sailor ashore and a sleeper asleep. German am Leben and Dutch in leven are the unfused cousins. English ran the phrase together; the grammar of the predicate is what remains of the old dative phrase.