cast iron

noun

"cast-iron" is a 8-letter English headword indexed on PlainSpell.

The verdict

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

Unranked
below top-frequency English
9
letters

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A hard and brittle, but strong, alloy of iron, carbon, and silicon, formed by casting in a mould.

Key facts for cast iron
PropertyValue
Headwordcast iron
LanguageEnglish
Part of speechNoun
Letters9
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “cast iron” sits in English frequency

cast iron 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

cast iron is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. Gloss: "A hard and brittle, but strong, alloy of iron, carbon, and silicon, formed by casting in a mould.".

cast iron has no tracked misspelling variants, and the word's spelling is regular enough that our generator found nothing worth flagging. No close-neighbour confusable shows up for this headword in our dataset, since nothing in our dataset looks or sounds close enough to cause mix-ups.

Etymologically, the entry records: Derived from the casting of this form of iron. See wrought iron for comparison. The correct English form is cast iron, spelled C-A-S-T- -I-R-O-N.

Definition

  1. 1
    A hard and brittle, but strong, alloy of iron, carbon, and silicon, formed by casting in a mould.

Etymology

Derived from the casting of this form of iron. See wrought iron for comparison.

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 "cast iron"?
"cast iron" is spelled C-A-S-T- -I-R-O-N.
What does "cast iron" mean?
As a noun, "cast iron" means: A hard and brittle, but strong, alloy of iron, carbon, and silicon, formed by casting in a mould.
What is the origin of the word "cast iron"?
Derived from the casting of this form of iron. See wrought iron for comparison. 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 “cast iron”

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

  • The one correct English spelling is C-A-S-T- -I-R-O-N - every other letter order is a misspelling in standard orthography.
  • 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