【Death】 , 【decease】 , 【demise】 , 【passing】 denote the end or the ending of life.
【Death】 is the general word and is used for the termination of plants and animals as well as of men and also of inanimate things marked by continuity or development.
【Decease】 and 【demise】 apply only to human beings except in figurative use. 【Decease】 is preferred in legal context but in ordinary use conveys a slightly euphemistic or rhetorical quality. 【Demise】 in literal use has become somewhat pompous or affected.
In figurative use it frequently lacks such connotation.
【Passing】 is a euphemism for the 【death】 of a person.
