hydro-

/ˈhaɪ.dɹoʊ/

//ˈhaɪ.dɹoʊ// prefix

"hydro" is a 5-letter English headword indexed on PlainSpell.

The verdict

“hydro-” is uncommon English (outside the top frequency list), classed as a prefix. The kind of spelling people second-guess.

Unranked
below top-frequency English
6
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - water

Key facts for hydro-
PropertyValue
Headwordhydro-
LanguageEnglish
Part of speechPrefix
IPA/ˈhaɪ.dɹoʊ/
Letters6
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “hydro-” sits in English frequency

hydro- falls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

hydro- is uncommon English outside the top frequency list, classed as aprefix, transcribed /ˈhaɪ.dɹoʊ/. Rarity is why readers land here mid-draft. 5 senses are on record.

Zero misspellings are on record for hydro- in our index, which points to an orthography that plays by predictable English rules. Our confusable-pair dataset has no match for it, suggesting its spelling stands apart enough that readers rarely confuse it with something else.

Etymologically, the entry records: From Ancient Greek ὑδρο- (hudro-), from ὕδωρ (húdōr, “water”). The correct English form is hydro-, spelled H-Y-D-R-O--.

Definition

  1. 1
    water
  2. 2
    liquid
  3. 3
    hydrogen
  4. 4
    a hydrous compound
  5. 5
    Hydrozoa

Etymology

From Ancient Greek ὑδρο- (hudro-), from ὕδωρ (húdōr, “water”).

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "hydro-"?
"hydro-" is spelled H-Y-D-R-O--. The IPA pronunciation is /ˈhaɪ.dɹoʊ/.
What does "hydro-" mean?
As a prefix, "hydro-" means: water
How do you pronounce "hydro-"?
The IPA (International Phonetic Alphabet) transcription for "hydro-" is /ˈhaɪ.dɹoʊ/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "hydro-"?
From Ancient Greek ὑδρο- (hudro-), from ὕδωρ (húdōr, “water”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Using “hydro-”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is H-Y-D-R-O-- - every other letter order is a misspelling in standard orthography.
  • Say it as /ˈhaɪ.dɹoʊ/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list