inefficiencyvsinefficientTell them apart

Quick tell: inefficiency is a noun, inefficient is an adjective, so they fill different roles in a sentence.

Which to use

“inefficiency” is a noun and “inefficient” is an adjective - they look or sound alike but fill different roles in a sentence.

#33,282
“inefficiency” frequency rank
#15,838
“inefficient” frequency rank
49120
confusion score

Side-by-Side Comparison

Feature inefficiency inefficient
Definition Lack of efficiency or effectiveness. Not efficient; not producing the effect intended or desired; inefficacious.

Letter map: inefficiency vs inefficient

Shared letters muted; letters that set inefficiency and inefficient apart highlighted. Shared run: 10.

12 ch
inefficiency
11 ch
inefficient

Grammar separator: inefficiency vs inefficient

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: inefficiency is anoun and inefficientanadjective. On the page they differ by 1 letter(s) in length. Our composite confusion score for this pair is 49120, derived from the frequency rank of both members and their visual similarity.

inefficiency is recorded at frequency rank #33,282, classified as anoun. inefficient is at rank #15,838, tagged as anadj, pronounced /ˌɪn.ɪˈfɪʃ.ənt/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 49120, this pair ranks #186,630 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of inefficiency vs inefficient

Shared letters: cefin. Private to "inefficiency": y. Private to "inefficient": t.

"inefficiency" · 12 letters · shape VCVCCVCVVCCV  ·  "inefficient" · 11 letters · shape VCVCCVCVVCC

Known mistypes of this pair

  • inefficiencyienfficiency · ineffciiency · inefficciency · inefficeincy · inefficiecny · inefficienccy · inefficiencyy · inefficienncy
  • inefficientienfficient · ineffciient · inefficcient · inefficeint · inefficiennt · inefficientt · inefficietn · inefficinet

Frequently Asked Questions

Is swapping "inefficiency" for "inefficient" ever safe?
No - they are not even the same part of speech. "inefficiency" is a noun and "inefficient" an adjective, so a sentence built for one is usually ungrammatical with the other.
In ordinary English text, does "inefficiency" or "inefficient" show up more?
"inefficient" is the more common of the two: it sits at frequency rank #15,838 in our English list, against #33,282 for "inefficiency". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Useful next steps

Pair "inefficiency" vs "inefficient" is on the table, pick a follow-up below.

  • Full dictionary entry for "inefficiency" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "inefficient" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #186,630 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "inefficiency" and "inefficient" also get mixed up with nearby pairs, the highest-scored neighbour is "inefficiency vs insufficiency". Nearby pair
  • Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #186,630 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

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

Source: FrequencyWords open word-frequency list