に就て[nitsuite] concerning
に就き[nitsuki] because of
去就[kyoshuu] committing one's self
就いては[tsuiteha] in line with this
就きましては[tsukimashiteha] in line with this

就く[tsuku] to ascend (the throne)
就ける[tsukeru] to install (a king, emperor, etc.)
就学[shuugaku] entering school
就学義務[shuugakugimu] compulsory school attendance
就学児童[shuugakujidou] school child

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