diff --git a/Library/Homebrew/manpages/brew.1.md.erb b/Library/Homebrew/manpages/brew.1.md.erb
index a82cd8c2f7..b2ce261cea 100644
--- a/Library/Homebrew/manpages/brew.1.md.erb
+++ b/Library/Homebrew/manpages/brew.1.md.erb
@@ -28,6 +28,28 @@ Homebrew is the easiest and most flexible way to install the UNIX tools Apple
 didn't include with macOS. It can also install software not packaged for your
 Linux distribution to your home directory without requiring `sudo`.
 
+## TERMINOLOGY
+
+**formula**: Homebrew package definition built from upstream sources
+
+**cask**: Homebrew package definition that installs macOS native applications
+
+**keg**: installation destination directory of a given **formula** version e.g. `/usr/local/Cellar/foo/0.1`
+
+**rack**: directory containing one or more versioned kegs e.g. `/usr/local/Cellar/foo`
+
+**keg-only**: a **formula** is **keg-only** if it is not symlinked into Homebrew's prefix (e.g. `/usr/local`)
+
+**cellar**: directory containing one or more named **racks** e.g. `/usr/local/Cellar`
+
+**Caskroom**: directory containing one or more named **casks** e.g. `/usr/local/Caskroom`
+
+**external command**: `brew` subcommand defined outside of the Homebrew/brew GitHub repository
+
+**tap**: directory (and usually Git repository) of **formulae**, **casks** and/or **external commands**
+
+**bottle**: pre-built **keg** poured into the **cellar**/**rack** instead of building from upstream sources
+
 ## ESSENTIAL COMMANDS
 
 For the full command list, see the [COMMANDS](#commands) section.
diff --git a/docs/Formula-Cookbook.md b/docs/Formula-Cookbook.md
index 7482d1813a..54f444cf40 100644
--- a/docs/Formula-Cookbook.md
+++ b/docs/Formula-Cookbook.md
@@ -8,6 +8,7 @@ A *formula* is a package definition written in Ruby. It can be created with `bre
 |----------------|------------------------------------------------------------|-----------------------------------------------------------------|
 | **Formula**    | The package definition                                     | `/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/foo.rb` |
 | **Keg**        | The installation prefix of a **Formula**                   | `/usr/local/Cellar/foo/0.1`                                     |
+| **Keg-only**   | A **Formula** is **Keg-only** if it is not linked into the Homebrew prefix | The [`openjdk` formula](https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/openjdk.rb) |
 | **opt prefix** | A symlink to the active version of a **Keg**               | `/usr/local/opt/foo `                                           |
 | **Cellar**     | All **Kegs** are installed here                            | `/usr/local/Cellar`                                             |
 | **Tap**        | A Git repository of **Formulae** and/or commands | `/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core`   |
diff --git a/docs/Manpage.md b/docs/Manpage.md
index c7cd03bdcf..e09277a257 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -12,6 +12,28 @@ Homebrew is the easiest and most flexible way to install the UNIX tools Apple
 didn't include with macOS. It can also install software not packaged for your
 Linux distribution to your home directory without requiring `sudo`.
 
+## TERMINOLOGY
+
+**formula**: Homebrew package definition built from upstream sources
+
+**cask**: Homebrew package definition that installs macOS native applications
+
+**keg**: installation destination directory of a given **formula** version e.g. `/usr/local/Cellar/foo/0.1`
+
+**rack**: directory containing one or more versioned kegs e.g. `/usr/local/Cellar/foo`
+
+**keg-only**: a **formula** is **keg-only** if it is not symlinked into Homebrew's prefix (e.g. `/usr/local`)
+
+**cellar**: directory containing one or more named **racks** e.g. `/usr/local/Cellar`
+
+**Caskroom**: directory containing one or more named **casks** e.g. `/usr/local/Caskroom`
+
+**external command**: `brew` subcommand defined outside of the Homebrew/brew GitHub repository
+
+**tap**: directory (and usually Git repository) of **formulae**, **casks** and/or **external commands**
+
+**bottle**: pre-built **keg** poured into the **cellar**/**rack** instead of building from upstream sources
+
 ## ESSENTIAL COMMANDS
 
 For the full command list, see the [COMMANDS](#commands) section.
@@ -2087,6 +2109,7 @@ See our issues on GitHub:
 
 [SYNOPSIS]: #SYNOPSIS "SYNOPSIS"
 [DESCRIPTION]: #DESCRIPTION "DESCRIPTION"
+[TERMINOLOGY]: #TERMINOLOGY "TERMINOLOGY"
 [ESSENTIAL COMMANDS]: #ESSENTIAL-COMMANDS "ESSENTIAL COMMANDS"
 [COMMANDS]: #COMMANDS "COMMANDS"
 [DEVELOPER COMMANDS]: #DEVELOPER-COMMANDS "DEVELOPER COMMANDS"
diff --git a/manpages/brew.1 b/manpages/brew.1
index f3fdf72aa5..9a9877eb95 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -15,6 +15,46 @@
 .SH "DESCRIPTION"
 Homebrew is the easiest and most flexible way to install the UNIX tools Apple didn\'t include with macOS\. It can also install software not packaged for your Linux distribution to your home directory without requiring \fBsudo\fR\.
 .
+.SH "TERMINOLOGY"
+\fBformula\fR
+    Homebrew package definition built from upstream sources
+.
+.P
+\fBcask\fR
+    Homebrew package definition that installs macOS native applications
+.
+.P
+\fBkeg\fR
+    installation destination directory of a given \fBformula\fR version e\.g\. \fB/usr/local/Cellar/foo/0\.1\fR
+.
+.P
+\fBrack\fR
+    directory containing one or more versioned kegs e\.g\. \fB/usr/local/Cellar/foo\fR
+.
+.P
+\fBkeg\-only\fR
+    a \fBformula\fR is \fBkeg\-only\fR if it is not symlinked into Homebrew\'s prefix (e\.g\. \fB/usr/local\fR)
+.
+.P
+\fBcellar\fR
+    directory containing one or more named \fBracks\fR e\.g\. \fB/usr/local/Cellar\fR
+.
+.P
+\fBCaskroom\fR
+    directory containing one or more named \fBcasks\fR e\.g\. \fB/usr/local/Caskroom\fR
+.
+.P
+\fBexternal command\fR
+    \fBbrew\fR subcommand defined outside of the Homebrew/brew GitHub repository
+.
+.P
+\fBtap\fR
+    directory (and usually Git repository) of \fBformulae\fR, \fBcasks\fR and/or \fBexternal commands\fR
+.
+.P
+\fBbottle\fR
+    pre\-built \fBkeg\fR poured into the \fBcellar\fR/\fBrack\fR instead of building from upstream sources
+.
 .SH "ESSENTIAL COMMANDS"
 For the full command list, see the \fICOMMANDS\fR section\.
 .