costly

/ˈkɒst.li/

//ˈkɒst.li// adj

By · According to Wiktionary data (CC BY-SA) ·

"costly" is a 6-letter English headword indexed on PlainSpell.

The verdict

“costly” has 10 generated spelling variants in the English index at frequency #7,899. The variants make it a useful spelling check.

#7,899
frequency rank, English
5,599
“C” headwords
10
tracked misspellings
13
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Of high cost; expensive.

Corpus desk

Index EN-costly · costly · English

costly · rank #7,899 · 10 variants · 13 confusables

  • FREQ-COMMON #7,899
  • LEN-LONG 6 letters
  • VOW-2 2 vowels
  • CONFUS-MID 13 pairs
  • VAR-MID 10 variants
  • BOOK-DENSE 5,599
  • PHOTO-FINISH conjunction

Nearest frequency peer: conjunction (-1 rank slots)

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.

Rank peers near misspelling magnet “costly”

Same rarity band: useful when a typo lands on a peer headword

corpus weight

What this shows “costly” sits among these FrequencyWords peers; misspelling depth is tracked separately in the edit-distance chart.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

costly vs cosy
67% similar
costly vs costs
67% similar
costly vs courtly
71% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for costly
PropertyValue
Headwordcostly
LanguageEnglish
Part of speechAdjective
IPA/ˈkɒst.li/
Letters6
Frequency rank#7,899
Misspellings tracked10
Confusable pairs13
SourceWiktionary (kaikki.org)

Frequency seat of misspelling magnet “costly”

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right).costlylands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Same rarity band neighbours include “conjunction” (#7,898), “cows” (#7,900), “committees” (#7,897). Among 5,599 “C” headwords, “costly” is #7,899. Source: FrequencyWords open word-frequency list.

A misspelling magnet

The generator records 10 spelling variants around costly (IPA /ˈkɒst.li/), anadjective. Corpus frequency is #7,899 among 5,599 “C” headwords. Dominant gloss: "Of high cost; expensive.".

Our generated misspelling index lists 10 likely wrong-spelling variants for costly, with forms such as "ccostly", "coslty", and "cosstly". Each variant is a distinct typo pattern an edit-distance generator flags, typically a doubled-consonant error, a silent-letter drop, or a vowel substitution. It also participates in 13 confusable-pair relationships, "cosy", "costs", "courtly", and more, where similar look or sound leads writers to substitute one word for another in context.

Etymologically, the entry records: From Middle English costly, costely, costeley, equivalent to cost + -ly. The correct English form is costly, spelled C-O-S-T-L-Y.

Definition

  1. 1
    Of high cost; expensive.

Recorded use

Wiktionary examples

These source excerpts show how costly appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. a costly activity
  2. a costly error

Etymology

From Middle English costly, costely, costeley, equivalent to cost + -ly.

Synonyms

dearexpensiveprohibitive

Antonyms

costlessly

This word in other languages

costoso(Español)coûteux(Français)teuer(Deutsch)custoso(Português)

Common misspellings

Also misspelled as:

  • ccostly
  • coslty
  • cosstly
  • costlly
  • costlyy
  • costtly
  • costyl
  • cotsly
  • csotly
  • ocstly

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of costly - expressed in single-character edits (insert, delete, or swap one letter). Bigger bars stand out at a glance; a one-edit slip is the hardest to catch.

ccostly1coslty2cosstly1costlly1costlyy1costtly1costyl2cotsly2
Edit distance from "costly"

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "costly"?
"costly" is spelled C-O-S-T-L-Y. The IPA pronunciation is /ˈkɒst.li/.
What does "costly" mean?
As an adjective, "costly" means: Of high cost; expensive.
What words are commonly confused with "costly"?
"costly" is commonly confused with "cosy", "costs", "courtly". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "costly"?
The IPA (International Phonetic Alphabet) transcription for "costly" is /ˈkɒst.li/. 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 "costly"?
From Middle English costly, costely, costeley, equivalent to cost + -ly. 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.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "costly", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 6 letters (nearest by frequency rank).

cycles#7,903darker#7,904Davies#7,905bundle#7,890

Similar misspelling depth

Headwords with a similar count of attested misspellings (10 here; floor ≥5).

implied10 variantsstorms10 variantsoffended10 variantspainter10 variants

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

Source: FrequencyWords open word-frequency list