death vs infant death

death and infant death both are nouns.

Word	Noun	Adjective	Verb	Adverb
death	Yes	No	No	No
infant death	Yes	No	No	No

As nouns, infant death is a hyponym of death; that is, infant death is a word with a more specific, narrower meaning than death:

death: the absence of life or state of being dead
infant death: sudden and unexpected death of an apparently healthy infant during sleep

death (noun)	infant death (noun)
the act of killing	sudden and unexpected death of an apparently healthy infant during sleep
the event of dying or departure from life
the permanent end of all life functions in an organism or part of an organism
the absence of life or state of being dead
a final state
the time when something ends
the time at which life ends; continuing until dead