サンプリング周波数[sanpuringushuuhasuu] sampling frequency
一周忌[isshuuki] first anniversary of death
一周期[isshuuki] period (in astronomy)
一周年[isshuunen] one full year
円周[enshuu] circumference

円周率[enshuuritsu] Pi (3.1415926..)
外周[gaishuu] outer circumference
基本周波数[kihonshuuhasuu] fundamental frequency
月経周期[gekkeishuuki] menstrual cycle
周章てる[awateru] to become confused (disconcerted, disorganized, disorganised)

比律賓[firippin] Philippines
一律[ichiritsu] evenness
一律減反[ichiritsugentan] reduction in area of rice under cultivation
韻律[inritsu] rhythm
黄金律[ougonritsu] The Golden Rule ("do unto others as you would have them do unto you")

音律[onritsu] metre
戒律[kairitsu] (religious) precept
紀律[kiritsu] order
軍律[gunritsu] martial law
刑律[keiritsu] criminal law

安全期[anzenki] safe period
暗黒期[ankokuki] eclipse period
一期[ichigo] one's life time
一期[ikki] one term
一期一会[ichigoichie] once-in-a-lifetime encounter (hence should be cherished as such)

一周期[isshuuki] period (in astronomy)
一定期間[itteikikan] fixed interval
延期[enki] postponement
延期になる[enkininaru] to be postponed
沖積期[chuusekiki] alluvial period