IRB

noun

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

"irb" is a 3-letter English headword indexed on PlainSpell.

The verdict

“IRB” sits in 20 confusable pairs (corpus #33,690) as a noun. The look-alike neighbours are the real trap.

#33,690
frequency rank, English
2,140
“I” headwords
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Initialism of institutional review board, a committee that reviews the designs of proposed experiments to confirm whether all the methods proposed are ethical.

Corpus desk

Index EN-irb · IRB · English

IRB · rank #33,690 · 0 variants · 20 confusables

  • FREQ-MID #33,690
  • LEN-MID 3 letters
  • VOW-1 1 vowel
  • CONFUS-HIGH 20 pairs
  • VAR-0 0 variants
  • BOOK-MID 2,140
  • PHOTO-FINISH intractable

Nearest frequency peer: intractable (-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.

Frequency neighbours of confusable “IRB”

Peers at similar corpus weight, separate from look-alike pairs below

corpus weight

What this shows Bars place “IRB” against nearest ranked English headwords, not a reprint of the confusable-pair desk.

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).

IRB vs is
0% similar
IRB vs it
0% similar
IRB vs IV
33% similar

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

Key facts for IRB
PropertyValue
HeadwordIRB
LanguageEnglish
Part of speechNoun
Letters3
Frequency rank#33,690
Misspellings tracked0
Confusable pairs20
SourceWiktionary (kaikki.org)

Corpus rank beside confusables of “IRB”

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).IRBlands here:

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

Scale is logarithmic (each tick is 10× rarer). Same rarity band neighbours include “intractable” (#33,689), “jabs” (#33,691), “inroads” (#33,688). Among 2,140 “I” headwords, “IRB” is #33,690. Source: FrequencyWords open word-frequency list.

Easy to mix with look-alikes

The spelling risk for IRB is neighbouring look-alikes ("is", "it", …), not just typos; it is anoun. Frequency #33,690 among 2,140 “I” headwords. 4 recorded senses keep meaning in play.

IRB has no tracked misspelling variants, since its letter pattern doesn't lend itself to common typo substitutions. It also participates in 20 confusable-pair relationships, "is", "it", "IV", and more, a pairing that trips writers up because the two words share enough sound or shape to blur together.

No documented word history exists for this headword, so spelling patterns must be inferred from the word's phoneme-to-grapheme mapping rather than from a documented borrowing chain. The correct English form is IRB, spelled I-R-B.

Definition

  1. 1
    Initialism of institutional review board, a committee that reviews the designs of proposed experiments to confirm whether all the methods proposed are ethical.
  2. 2
    Initialism of investment review board, a committee of business executives who review investment choices, comparing against strategy and opportunity costs.
  3. 3
    Initialism of internal review board, an internal affairs division of a police department.
  4. 4
    Initialism of inflatable rescue boat.

Recorded use

Wiktionary example

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

  1. Ms Rybicki began filming just as a second IRB drove out to the rogue boat, collecting the first lifesaver into the boat en route.

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 "IRB"?
"IRB" is spelled I-R-B.
What does "IRB" mean?
As a noun, "IRB" means: Initialism of institutional review board, a committee that reviews the designs of proposed experiments to confirm whether all the methods proposed are ethical.
What words are commonly confused with "IRB"?
"IRB" is commonly confused with "is", "it", "IV". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
What language does "IRB" come from?
"IRB" is a English word. You can look up definitions, pronunciations, and spelling data for this and other words across English, Spanish, Portuguese, French, and German on PlainSpell.
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 "IRB", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 3 letters (nearest by frequency rank).

GTS#33,666LRT#33,718FEC#33,647ESC#33,641

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

Source: FrequencyWords open word-frequency list