事前に必要[jizennihitsuyou] prerequisite
生者必滅[shoujahitsumetsu] All living things must die
絶対必要[zettaihitsuyou] absolutely necessary
必ず[kanarazu] always
必ずしも[kanarazushimo] (not) always

必ずや[kanarazuya] certainly
必携[hikkei] handbook
必見[hikken] worth seeing
必殺[hissatsu] certain kill
必死に[hisshini] frantically

鬼利死丹[kirishitan] early Japanese Christianity (from the later Muromachi period)
あっ死[asshi] crushing to death
安楽死[anrakushi] euthanasia
一死[isshi] dying
一死後[isshigo] after one out (in Baseball)

一死報国[isshihoukoku] dying for one's country
煙死[enshi] death by smoke suffocation
横死[oushi] violent (tragic or accidental) death
仮死[kashi] asphyxiation
過労死[karoushi] death from overwork and mental stress