契り[chigiri] pledge
契る[chigiru] to pledge
契印[keiin] impression of a seal over the joint of two papers
契機[keiki] opportunity
契約[keiyaku] contract

契約期間[keiyakukikan] contract period
契約書[keiyakusho] (written) contract
信託契約[shintakukeiyaku] trust agreement
双務契約[soumukeiyaku] bilateral agreement
二世の契り[nisenochigiri] marriage vows

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

安全保障条約[anzenhoshoujouyaku] US-Japan Security Treaty
違約[iyaku] breach of contract
違約金[iyakukin] penalty for contract breach
一粒子既約[ichiryuushikiyaku] one particle irreducible (physics)
化学兵器禁止条約[kagakuheikikinshijouyaku] chemical weapons ban treaty

仮条約[karijouyaku] provisional treaty
会う約束[auyakusoku] rendezvous
会員規約[kaiinkiyaku] membership agreement (e.g. for a credit card)
解約[kaiyaku] cancellation of contract
確約[kakuyaku] firm promise

あっとゆう間に[attoiumani] just like that
此間[konaida] the other day
此の間[konokan] the other day
間誤付かせる[magotsukaseru] to fluster
間誤付く[magotsuku] to be confused

クローン人間[kuroonningen] (human) clone
シゾイド人間[shizoidoningen] schizoid person
ベクトル空間[bekutorukuukan] vector space
π中間子[paichuukanshi] pi meson
位相空間[isoukuukan] phase space (physics)