The canonical register: Hýdra
A letter to a colleague, 31 July 2026 — on the name Hýdra, and on the forms that keep failing it.
Your note said, roughly: surely the marks are a nicety. Permit me to use Hýdra to show they are not.
First, the attestation. The name is attested as Ὕδρα, in the attestation LSJ and Beekes, Etymological Dictionary of Greek give us. On the evidence, it means "Water serpent". The canonical transliteration is Hýdra.
And the marks themselves: y → ý (Acute on y). Remove any one of them and you have not simplified the name — you have told a small lie about it, and references are built of exactly such small truths.
Say it aloud as the sources heard it: 'HOO-drah' — the first syllable is pitched high and begins with a rough 'h'; the final -a is short. The marks are what carry that sound to a reader who has never heard it spoken.
On the plain form — and I want to be precise, because you pushed on this. The plain form hydra is not false — it is a fallback, and the register is exact about what that means. In systems that cannot carry diacritics (legacy databases, older tooling, parts of the address-bar pipeline) the flattened form is the accepted vehicle, and the rulebook names it explicitly as the final rung of the fallback hierarchy: full restoration first, circumflex where attested, macron-only by the academic standard, an attested variant, and only then plain ASCII.
What the fallback status forbids is promotion: hydra may carry the name where marks are impossible, but it may not represent the name where marks are possible. Every mark it drops — y → ý — is a fact the sources recorded. A fallback is a vehicle, never the primary.
Now to the forms that provoked your letter. As for Hýdrá́: it comes from the English ear — English speakers slam the first syllable of every borrowed name (DEL-fi, MY-cene), so the accent drifts forward online, and it fails because moves the stress from y (where the Greek puts it) to A — a different word with a different rhythm; the sources stress y and nothing else As for Hýdra: it comes from the circumflex habit — writers who learned that "the little hat means Greek" and apply it wherever an acute belongs, and it fails because the source carries an acute (oxeia, a rising tone), not a circumflex (perispomene, a rise-fall): the two marks are different facts about pitch, and only the acute is attested on y
One more thing, because it always surprises: the name did not stay home. The Hydra has no independent cult but belongs to a broader Greek and Near Eastern tradition of multi-headed water serpents defeated by storm-gods or heroes. The Lernaean Hydra influenced later dragon lore, including medieval accounts of regenerating dragons.
And it never stopped working. 'Hydra-headed' has become an idiom for any problem that grows worse when attacked. The monster appears in comic books, films, and political metaphors as the image of resilient, multiplying evil.
The Convention's Own History
The marks this register defends were not invented for typesetting. Ancient Greek carried a melodic pitch accent, and the acute and circumflex were added by Alexandrian scholars — Aristophanes of Byzantium, tradition holds — precisely to preserve it when the spoken language began to level. Vowel quantity (the macron's concern) is older still: it changes meter, meaning, and grammar, and the poets of the Theogony depend on it. To drop either class of mark is to drop two millennia of deliberate preservation. The restored-stress convention simply continues the oldest documented project in European scholarship: keeping the sound of Greek alive in its letters.
Where Protocol Meets Practice
The technical answer is simple: the canonical marks are legal IDNA 2008 characters, encoded as punycode under `xn--`. The practical answer is messier: legal does not mean stocked (registrar inventory is partial), and stocked does not mean typeable (stacked diacritics defeat mobile keyboards).
So the register's rule is a hierarchy of attested forms — full restoration, circumflex, macron-only, attested variant, and finally plain ASCII for the systems that cannot carry marks. Every rung is defensible because every rung is attested. The forms this register rules against are not rungs; they are errors, and errors do not get rungs.
Write back when you have checked the sources; they are better company than I am.
— The Register
The Verdict
Hýdra is the canonical form: attested, checkable, and enforced across the temple, the lexicon, the cards, the APIs, and this register. The plain form hydra is sanctioned as the fallback vehicle and nothing more. The false forms above are documented so that no reader has to take the temple's word on faith — the violations are stated, the sources are named, and the register stands open to challenge on every line.
The temple of Hýdra stands at /sites/hydra/.
The docket for this ruling: 2 false forms ruled against, Hýdrá́ first on the docket; 1 preserved mark verified: y → ý; no contested forms attested; the attestation rests on 6 cited sources — LSJ, Beekes, Etymological Dictionary of Greek, Apollodorus, Bibliotheca.
The Register Continues
The register holds 287 entries like this one — each temple with its own ruling. Read the temple's founding dispatch for the story, its Restoration File for the philology, its Resonance File for the industries, or the whole archive end to end.
Continue the register — previous entry: Huītzilōpōchtli (read it) · next entry: Hygíeia (read it).
The Canonical Register is written from the same canonical record as the lexicon itself. If a false form is missing from this page, it is because the evidence does not support calling it false — or because we have not seen it yet. Show us, with a citation, and the register will answer.