Dead, defunct, deceased, departed, late, lifeless, inanimate all mean devoid of life.
Dead applies strictly to anyone or to anything that has been deprived of life and has therefore ceased to grow or to function.
Dead is also applicable to things which have not had life (in its literal sense) but have existed for a time and have been used or accepted or have proved effective or influential; thus, a dead language is no longer in spoken use by any people; a dead belief no longer has any acceptance; a dead journal no longer is printed and circulated; a dead issue or question no longer arouses interest or debate.
Figuratively the term implies lack or loss of sensation, consciousness, feeling, activity, energy, or any of the qualities associated with life.
Defunct differs little in its literal sense from dead, except that it is somewhat bookish. The term is more often applied to a thing that by failure or dissolution has ceased to function or to operate.
Deceased applies only to a person and especially to one who has died comparatively recently or who, though dead, is at the moment under consideration especially in some legal context.
Departed is distinctly euphemistic (especially in religious use). Late is used in place of deceased or departed especially when stressing a relationship to a surviving person or an existent institutionc.
Lifeless, unlike the preceding words, does not necessarily imply deprivation of life, for it is applicable not only to something literally dead but also to something which never had life or is incapable of life.
In comparison with dead, however, lifeless stresses the absence (sometimes, when loss of consciousness is implied, the apparent absence) of the phenomena characteristic of being alive; thus, one speaks of a dead man, but a lifeless body (that is, a body that shows no signs of life).
In its extended use lifeless is especially applicable to things (far less often to persons) that have not or never have had vitality, power, or spirit.
Inanimate is more consistently used than lifeless in describing something which never had life; it is the preferred term when a contrast between that which is devoid of life and that which possesses life is expressed or implied.
But inanimate is also applicable in extended use to that which is spiritless, inactive, or not lively, and therefore dull.