/ ˈɪnfənsi; NAmE / noun [ U ]
1.
the time when a child is a baby or very young :
to die in infancy
2.
the early development of sth :
a time when the cinema was still in its infancy
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WORD ORIGIN
late Middle English : from Latin infantia childhood, inability to speak, from infans , infant- unable to speak, from in- not + fant- speaking (from the verb fari ).