efficiencyvsefficientlyConfusable pair

Quick tell: efficiency is a noun, efficiently is an adverb, so they fill different roles in a sentence.

Which to use

“efficiency” is a noun and “efficiently” is an adverb - they look or sound alike but fill different roles in a sentence.

#3,749
“efficiency” frequency rank
#9,739
“efficiently” frequency rank
13488
confusion score

Side-by-Side Comparison

Feature efficiency efficiently
Definition The extent to which a resource is used for the intended purpose. In an efficient manner.

Letter map: efficiency vs efficiently

Shared letters muted; letters that set efficiency and efficiently apart highlighted. Shared run: 9.

10 ch
efficiency
11 ch
efficiently

Grammar separator: efficiency vs efficiently

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: efficiency is anoun and efficientlyanadverb. On the page they differ by 1 letter(s) in length. Our composite confusion score for this pair is 13488, derived from the frequency rank of both members and their visual similarity.

efficiency is recorded at frequency rank #3,749, classified as anoun, pronounced /ɪˈfɪʃ.ən.si/. efficiently is at rank #9,739, tagged as anadv.

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 13488, this pair ranks #475,487 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of efficiency vs efficiently

Shared letters: cefiny. Private to "efficiency": -. Private to "efficiently": lt.

"efficiency" · 10 letters · shape VCCVCVVCCV  ·  "efficiently" · 11 letters · shape VCCVCVVCCCV

Known mistypes of this pair

  • efficiencyeffciiency · efficciency · efficeincy · efficiecny · efficienccy · efficiencyy · efficienncy · efficienyc
  • efficientlyeffciiently · efficciently · efficeintly · efficienlty · efficienntly · efficientlly · efficientlyy · efficienttly

Frequently Asked Questions

Do "efficiency" and "efficiently" mean the same thing in a sentence?
No - they are not even the same part of speech. "efficiency" is a noun and "efficiently" an adverb, so a sentence built for one is usually ungrammatical with the other.
Frequency check: "efficiency" vs "efficiently" - which ranks higher?
"efficiency" is the more common of the two: it sits at frequency rank #3,749 in our English list, against #9,739 for "efficiently". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Pair "efficiency" vs "efficiently" is on the table, pick a follow-up below.

  • Full dictionary entry for "efficiency" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "efficiently" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #475,487 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "efficiency" and "efficiently" also get mixed up with nearby pairs, the highest-scored neighbour is "efficient vs efficiently". 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 #475,487 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