Text Processingflags: gi

Word Boundary (Whole Word Match)

Match the whole word `cat` without matching it inside other words like `concatenate` or `category`.

Try it in RegexPro →

Available in

JSSupported

JavaScript / ECMAScript

Browser-native RegExp. Default if you don't pick.

PYSupported

Python (re)

CPython stdlib `re`. Unicode-aware `\w` and `\d` by default.

GOSupported

Go (RE2)

Linear-time matching. No backreferences or lookarounds.

Pattern

regexengine-agnostic
\bcat\b   (flags: gi)

Raw source: \bcat\b

How it works

\b is a zero-width assertion at a word boundary — the position between a word character (\w) and a non-word character (or string edge). Wrapping `cat` in two \b anchors forces the match to start AND end at word boundaries, so `cat` matches but `concat` and `cats` do not.

Examples

Input

The cat sat on the mat.

Matches

  • cat

Input

I will concatenate the strings.

No match

—

Input

CAT, Cat, cat — all match.

Matches

  • CAT
  • Cat
  • cat

Common use cases

  • •Find-and-replace targeting whole words only
  • •Search-engine-style keyword highlighting
  • •Linting for forbidden whole-word identifiers
  • •Tokenizer fallback in NLP pipelines

Related patterns

Duplicate Word

Text Processing

Detects consecutive duplicate words using a backreference.

Sentence Boundary

Text Processing

Matches sentence boundaries (punctuation followed by whitespace and a capital letter).

Hashtag

Text Processing

Match hashtags (# followed by word characters) in social media posts, including accented Latin characters.

HCL / Terraform Variable Reference

Text Processing

Match Terraform / HCL references like `var.name`, `local.foo`, `module.x.output`, or `data.aws_ami.ubuntu.id`.

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