サイ  
ふたた.び 
() again () twice () second time
さい (pref) re-, again, repeated, deutero-, deuto-, deuter-
ふたたび (adv) again, once more, a second time
さいスタート (n,vs) restarting
さいえん (n,vs) (1) another showing (of a play), (2) recapitulation (biology)
さいかい (n,vs) another meeting, meeting again, reunion
さいかい (n,vs) reopening, resumption, restarting
さいかいはつ (n,vs) redevelopment
さいき (n,vs,adj-no) comeback, recovery, restoration, rally, reflexive (in grammar)
さいけん (n,vs) rebuilding, reconstruction, rehabilitation
さいけんとう (n,vs) re-examination, review, reappraisal
さいげん (n,vs,adj-no) reappearance, reproduction, return, revival
さいこう (n,vs) reconsideration
さいこん (n,vs) second marriage
さいさん (adv,n) again and again, repeatedly
さいしん (n,vs) review, revision, reexamination, retrial
さいせい (n,vs,adj-no) playback, regeneration, resuscitation, return to life, rebirth, reincarnation, refresh, narrow escape, reclamation, regrowth
さいせん (n,vs) re-election
さいど (n-adv,n-t) twice, again, second time
さいにん (n,vs) reappointment
さいねん (n,vs,adj-no) recurrence, revival, resuscitation
さいはつ (n,vs) return, relapse, reoccurrence
さいはん (n) resale
さいへん (n,vs) reorganization, reorganisation, reshuffle
さいらい (n,vs) return, second coming, second advent, reincarnation
さらいげつ (n-adv,n-t) month after next
さらいしゅう (n-adv,n-t) week after next
さらいねん (n-adv,n-t) year after next

Links: KanjiDic: EDict : Wikimedia
Etymologies: 中文字譜 : 説文解字