Mayjay: Japanese-English Dictionary

main Mayjay window

What is Mayjay?

Mayjay is a Japanese-English dictionary. You type a word, then type enter. Mayjay displays definitions.

You can type Japanese with kanji or hiragana, or katakana for loanwords. If you do not know kanji, you can type the reading in hiragana, if you know it or can find it (furigana is your friend).

You can type English. The JMdict dictionary data that Mayjay displays is biased towards English definitions of Japanese terms, so English-to-Japanese lookups do not always produce useful results. Try a few English synonyms and maybe you will find a good Japanese match.


You can use type a single asterisk * to stand for zero or more characters. Mayjay does not support multiple wildcards in a single string.

Mayjay places implicit wildcards at the start and end of any search string, you do not need to.

Search Tips

System Requirements

Java 1.4.1

Japanese Input/Display




Mac OS X

  1. Open Mayjay.dmg to make the Mayjay disk image appear on your desktop.
  2. Drag the Mayjay application out of the Mayjay disk image onto your hard disk.


  1. Unzip
  2. Drag and mayjay.bat to your hard disk
  3. If you want, make a shortcut to the mayjay.bat file and add that shortcut to your Start Menu/Programs menu.

Some Windows java installations allow you to double-click a .jar file to launch that application. If that works for you, great.


  1. Unzip
  2. launch with java -jar mayjay.jar


Application Menu (Mac OS X Only)

app menu

Same as other Mac OS X application menus.

File Menu

file menu

Open XML Dictionary... is how you load a new JMdict file. Mayjay comes with a dictionary preloaded. You will likely never need to use this command.

Why use this command? If you get a newer or different dictionary data file, this is how you load it. Or if you change Java virtual machines and find that the pre-loaded dictionary file is incompatible with your JVM's binary storage format.

Open XML Dictionary creates a new dict.dat file in the current directory. This file contains the dictionary entries and a lookup index, and is usually 1/3 to 1/2 the size of the JMdict file that created it. Mayjay can load a dict.dat file in about half the time and 1/10th the memory that it takes to load a JMdict file. Mayjay contains the dict.dat file for the JMdict file that was available in April 2003.

Open XML Dictionary... requires over 400MB of memory. This exceeds Java's default heap size and fails with an error message. To give Mayjay enough memory to complete this command, launch Mayjay with the command line java -Xmx400m -jar mayjay.jar. Once Mayjay parses JMdict file, you no longer need to use the -Xmx400m command line.

Edit Menu

edit menu

The usual Edit menu. Undo? Not in Mayjay.

Recent Menu

recent menu

Mayjay remembers your last 10 lookup strings. Select them from this menu to look them up again. The Back command takes you to your previous lookup.

Font Menu

font menu

The Font menu lets you choose a different font. It displays a font dialog with a list of fonts capable of displaying Japanese and English. Pick any font from this list and Mayjay's main window immediately reflects the change. There are also two font size lists, one for the entry field where you type, and another for the definition list.

Mayjay remembers your font choice even after you quit and relaunch Mayjay.

font dialog

font dialog, Hiragino Mincho W3

font dialog, Osaka Mono

Why Mayjay? What does Mayjay mean?

Mayjay is not a real word, not in English, not in Japanese. It is a contraction of the English word May and the English letter J. It means only that I started this project in May, and used Java (J).

Starting in 2002, I dabbled with writing a dictionary reader, in spare hours here and there. Over the months, I created 5 or 6 dictionary projects, written in various programming languages and frameworks. Of those 5 or 6 projects, the Java project I started in May 2002 developed fastest into a usable dictionary. After using Mayjay privately for over a year, the name stuck.

Known Bugs

If you find a bug, send an email to mayjay

There are a few bugs that I cannot figure out. All of these bugs occur using Java 1.4.1 on Mac OS X 10.2.4:


Big thanks to Mark Wittenberg for being Mayjay's first tester. He spent hours getting an early version of Mayjay to work on Linux.

Thanks to Jim Breen for his EDICT and JMdict projects. His work in making electronic dictionary data available to us geeks has spawned dozens of little dictionary projects, including Mayjay.

Other Resources

Jim Breen's Japanese Page

Mayjay would not exist without Jim Breen's Japanese Page. He worked to collect the dictionary data and publish it in a form usable by programmers. He got the copyright and license all sorted out, and allowed geeks like me to publish readers for his data. Read the whole page for the amazing list of projects his work has spawned.


Tejina is a cool Java application that lets you draw kanji and get definitions for them. You have to know enough about kanji to get the stroke order mostly correct, but it gives you a list of possible matches, and usually about 1/3 to 1/2-way through the drawing, you can pick the kanji from the list.

I also really like the stroke order animation. When I do not recognize a radical (or just plain forget some tricky stroke order), Tejina can draw the kanji for me. Very nice.

Tejina is not a dictionary: it does not give you multi-kanji definitions. So although you can learn that 音 has several meanings (sounds, tone, note), you will not learn that 音楽 means music. This is not really what Tejina is intended for. That is where dictionaries come in.


A beautiful JMDict viewer for Mac OS X. Like Mayjay, its interface is simple. Unlike Mayjay, its interface was written using native Mac OS X technologies, making it far more elegant.

If you are looking for a Japanese/English dictionary for Mac OS X, I recommend checking out Tensai, rather than my own Mayjay.


From Incors, the same folks who bring you Tejina: a new kanji every day. It is a web page with a single kanji, its readings and meanings, and a list of several multi-kanji words using that kanji.


JEDict is another Japanese/English dictionary program, also using the dictionary data files from Jim Breen's Monash University work. Written in Carbon for Mac OS 8.1, Mac OS 9, and Mac OS X, this application is pretty powerful. It includes a effective kanji lookup system by component, and a handwriting recognizer. I've been playing with JEDict for a while now, and it might just be good enough to replace the Tejina+Mayjay combination I've been using for so long.


JavaDict is a kanji dictionary. It contains several methods for looking up kanji, including drawing, radical/bushu, and skip method.


Mayjay was written by Zig Zichterman.

You can reach Zig Zichterman at mayjay

The most recent version of Mayjay is at

Mayjay: GNU Public License

Mayjay is released uder the GNU Public License.

Mayjay is free: you do not owe anybody any money for it. It's just a cheesy little viewer app, after all.

Mayjay is free software: you have the freedom to use this software as you wish, modify it, redistribute it, hire somebody to change it, just about anything. There are a few restrictions: if you redistribute it, you are required to abide by the same GNU Public License that came with Mayjay. This basically means you are free give it to your friends, as long as you give the entire thing to your friends.

Full source code to Mayjay is included in src.jar. You should have received this source code archive with your copy of Mayjay.

Dictionary Data is Copyright Monash University

The dictionary data in Mayjay is Copyright © 2003 The Electronic Dictionary Research and Development Group, Monash University.

Jim Breen and Monash University are kind enough to make this data available for use and redistribution in projects such as Mayjay.

To keep download sizes lower, the original XML source for JMdict is not included in Mayjay distributions. Mayjar.jar contains a file dict.dat that includes a subset of JMdict's data, using only English meanings and Japanese headwords.

Change History

04/23/03 1.0.1 improvements to word ranking for English text
04/19/03 1.0 initial public release