Why is the inhabitant of a country called a “citizen”, instead of a "countrizen"?

Why is citizen used to describe an inhabitant of a country when the word is derived from the Latin for city (civitas) and originally meant a city dweller?

Wouldn’t the nouns derived from ‘country’ or ‘nation’ (national) be more appropriate?

Solution 1:

OED has a note on citizen:

The semantic development has been influenced by classical Latin cīvis (see civic adj.)

It seems like the semantic drift in citizen, civilian, civic, etc. from "city-dweller" to one with legal rights within any governed community involves both legal and military history.

In an early shift, it seemed to refer to legal disputes between private individuals as opposed to a military or criminal dispute.

civil plea a legal proceeding relating to civil law, as opposed to criminal or (formerly) ecclesiastical law; a plea brought in a civil court, a civil action.

Following that angle, the importance of membership to a city vs. membership in any society became less important than the law under which a citizen dispute occurred.

Given the importance of Latin in these etymologies, I wouldn't be surprised if references to "citizens of Rome" led to some ambiguity. (Rome is the object in the oldest dated reference to general social membership in OED's cited uses -- from a bible translation.)

Solution 2:

Summary

The English word ‘citizen’ is of Anglo-Norman vintage and was initially used to mean a city dweller, but soon acquired the current alternative meaning, which eventually became dominant. ‘Countryman’ (not ‘countrizen’) is the noun derived from ‘country’, but acquired a slightly different meaning as illustrated by ‘fellow countryman’, and was able to exist in concert with ‘citizen’. ‘Countryman’ can also be used to mean someone with a rural abode, so is no less ambiguous. ‘National’ has only been used as a noun in this sense more recently and is often used with a different shade of meaning. Whether or not the alternatives would have been more appropriate is a matter of opinion, but no native speaker cares.

Origin and use of ‘citizen’

According to the 1928 edition of the Oxford English Dictionary (OED), the first meaning of the word was a city dweller:

1. An inhabitant of a city or (often) a town ; esp. one possessing civic rights and privileges, a burgess or freeman of a city.

…and the first example it quotes illustrates this

“1314…Þe citiseins of Þat cite wel often god Þonked he”

There follows an example from 1514 in which ‘citizen’ is used in explicit contrast to ‘countryman’ — meaning a rural dweller. (It is also used in contrast to soldier.) Another such example is as late as the 19th century, but I suspect the modern meaning had overtaken it by then.

The more usual modern meaning is given by the OED as

2. A member of a state, an enfranchised inhabitant of a country, as opposed to an alien…

and the first example quoted occurs less than a century after that of the original meaning, associating a citizen with a region rather than a city:

“ c 1384 In this Region certeyn Duelleth many a Citezeyn…”

The association of rights and privileges with the original meaning of ‘citizen’ suggests to me that the extension of the word may have seemed acceptable because it implied not where one lived, but the rights and privileges that were a consequence of one's nationality. (But this is just a suggestion.)

Origin and use of alternatives derived from the word ‘country’

The OP clearly feels that a noun derived from the word ‘country’ would be more appropriate than one derived from ‘city’, but is wide of the mark in suggesting ‘countrizen’. The suffix ‘izen’ is not used to form a noun for inhibitant in English in any other case (see the OED entry for ‘citizen’) and there is, in fact, a word formed from ‘country’ in the normal manner of adding ‘man’ (sometimes with a feminine form ‘woman’) — countryman.

Indeed, according to the OED, the use of ‘countryman’ to indicate an inhabitant of a particular nation predates that same use for ‘citizen’, with the first example cited in 1305. The definition given:

1. A man of a (specified or indicated) country or district… ; a native or inhabitant, often in comb…

This usage has more or less died out expect in relation to districts, e.g. “north-countryman”.

More common is the similar but distinct usage (first OED example 1425):

2. A man of one’s own country, a fellow-countryman ; usually with possesive

This co-existed with citizen because they were used in different ways. e.g.

“I was supported by my countrymen, stalwart English citizens all.” (my contrived example)

In addition, ‘countryman’ was no less ambiguous than ‘citizen’, as from 1577, or earlier, there was (as already alluded) the meaning”

3. One who lives in the country or rural parts and follows a rural occupation ; a husbandman

Origin and use of ‘a national’

A Google ngram comparison of “a British citizen” and “a British national” finds almost no examples of the latter. (Similar results are obtained substituting ‘American’ for ‘British’.) This just emphasizes the less frequent use of ‘national’ (noun) compared with ‘citizen’. The first example cited by the OED in its modern sense is from the late 19th century when it was clearly a neologism:

4. pl. in recent diplomatic use (after Fr nationaux) : Persons belonging to the same nation ; (one’s) fellow-countrymen.

with the example:

“1887 Each of these Consuls or Ministers has extensive power over his own nationals”

This illustrates the tendency to use the term in situations in which people are living in a country other than that for which they hold nationality.

To complicate things further, there is a formal difference between British Citizenship and British Nationality, which is explained on the Government website. I am not aware that the such a distinction exists in the US.

Why citizen?

I’m not sure that this is a very useful type of question. Of course, in some circumstances one can trace the displacement of one word by another to specifics, such as television or the internet. However, in many cases a word is introduced into a language, changes its meaning, and nobody worries about what it originally meant.

As I have explained, there was a word ‘countryman’, related to the noun ‘country’, but this was and is used in a slightly different sense, and, with its rural connotation, is no less ambiguous than ‘citizen’.

The word ‘national’ may be less ambiguous, but arrived much later on the scene, probably, as already mentioned by others, because the idea of a nation state arose much later.

Footnote for British citizens (and others)

The British Prime Minister, Teresa May, may have said:

“But if you believe you’re a citizen of the world, you’re a citizen of nowhere.”

However this extended use of citizen (“One who is at home and claims his rights everywhere”) was used in Britain as early as 1474, according to the OED:

“Helde hym bourgeys and cytezeyn of the world.”

Of course Cicero was using it (in Latin) — civem totius mundi — long before then.