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 September 3, 2026) - water

Corpus desk

Index EN-hydro · hydro- · English

hydro- · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-LONG 6 letters
  • VOW-2 2 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "H" thin
  • PHOTO-UNK Peer pending

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

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

Long-tail rank of “hydro-” in English

hydro-sits beyond the 100,000 most-frequent English words, in the long tail of technical, archaic, or otherwise rare vocabulary where spelling doubt tends to strike hardest.

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.

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

Source: FrequencyWords open word-frequency list