期 - A Square Lunar Calendar Shows TERMS of the Moon

Readings & Meanings:

キ

ゴ

term

Common Usage:

期末試験

同期

末期（まっき）

Examples:

期末試験は学年でトップだった。

同期の卒業生を連絡を取り合っている。

末期ガン患者の治療にあたる。

Translations:

My final exam was the top in my class.

I'm getting in touch with other graduates in the same class as me.

The treatment of the patient with the last stages of cancer was successful.

Radical:

月 is the radical, and here it is definitely derived from the moon kanji.

其 is the phonetic, and it means "that" now but originally was the pictograph of a square device for winnowing grain, plus a desk.

Square/rectangular and moon leads to the idea of a period or cycle, as in the fixed phases of the moon.

References:

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