御食い初め[okuizome] weaning ceremony
為初め[shisome] outset
為初める[shisomeru] to begin to do
仮初[karisome] temporary
業界初[gyoukaihatsu] the industry's first ...

月初め[tsukihajime] beginning of month
最初[saisho] beginning
初めに[hajimeni] to begin with (used as an introduction)
初めは[hajimeha] at first
手初めに[tehajimeni] at first

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

一段[ichidan] more
一段動詞[ichidandoushi] ichidan verb (one of the two main conjugation classes of verbs in modern Japanese, usually ending in -eru or -iru)
一段落[ichidanraku] completing the first stage
階段[kaidan] stairs
格段[kakudan] special

計画段階[keikakudankai] planning stage
決済手段[kessaishudan] method of payment
減段[gentan] reduction (of crop size)
五段[godan] Japanese verb group
五段動詞[godandoushi] godan verb (one of the two main conjugation classes of verbs in modern Japanese, usually ending in -u, -ku, -su, -tsu, -gu, -bu, -mu, etc.)

位階[ikai] court rank
位階勲等[ikaikuntou] court rank and honors
一階[ikkai] one floor
音階[onkai] musical scale
下層階級[kasoukaikyuu] proletariat

階下[kaika] lower floor
階級[kaikyuu] (social) class
階級章[kaikyuushou] rank insignia
階級闘争[kaikyuutousou] class struggle