喜 - Oh JOY, a Feast!

Readings & Meanings:

キ

よろこ（ぶ）

joy, happy

Common Usage:

大喜び

喜々（嬉々）

Examples:

試験に合格したので家族が大喜びした。

彼女は喜々とした様子で先生に報告に行った。

Translations:

Because I passed my exam, my family were overjoyed.

She, with a gleeful countenance, went to report to the teacher.

Radical:

口 is the radical, on the bottom, indicating mouth.

The rest is a pictograph showing a serving pot on a stand with a stack of food.

Combine them and you get the idea of a feast, which indicates joy. At least, that's what I feel at a feast.

The sound mimics what the Japanese thought of as the sound of a happy, joyous person, especially in 喜々, KEE-KEE, a high-pitched squeal of joy.

Bonus: 犬は喜び...

I first learned this word in my winter in Japan. It's part of a folk song that everybody knows:

Yuki ya konko arare ya konko.
Futte mo futte mo mada furi yamanu.
Inu wa yorokobi niwa kake-mawari,
neko wa kotatsu de maruku naru.

You can hear how the song goes here: http://www3.u-toyama.ac.jp/niho/song/yuki/yuki_e.html

References:

http://www.kanjinetworks.com/indices/radindex.html
http://www.thejapanesepage.com/node/kanji/ki.htm