infancy

noun

in·​fan·​cy ˈin-fən(t)-sē 

plural infancies

1

: early childhood

2

: a beginning or early period of existence

3

: the legal status of an infant

Examples of infancy in a Sentence

She was often sick during her infancy.

a skill developed in infancy

She has been a member of the church since its infancy.

Recent Examples on the Web

People born with his rare genetic disease, a type of urea-cycle disorder, have about a 50 percent chance of living past infancy. —Nancy Walecki, The Atlantic, 8 Dec. 2025

Babies exposed to hepatitis B at birth or in infancy have a 90% chance of developing chronic hepatitis B, which carries long-term risks of liver cancer and other life-threatening complications. —Christopher Harris, CBS News, 5 Dec. 2025

Immunization in infancy confers lifelong protection against the hepatitis B virus, which can cause serious, potentially fatal health problems including liver cancer and cirrhosis. —Pien Huang, NPR, 5 Dec. 2025

The strange pliable substance, which NASA said is not unlike used gum or soft plastic, was likely formed when our solar system was in its infancy. —Eric Lagatta, USA Today, 4 Dec. 2025

Word History

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing infancy

• in one's infancy

Kids Definition

infancy

noun

in·​fan·​cy ˈin-fən-sē 

plural infancies

1

: early childhood

2

: a beginning or early period of existence

Medical Definition

infancy

noun

in·​fan·​cy ˈin-fən-sē 

plural infancies

1

: early childhood

2

: the legal status of an infant

Legal Definition

infancy

noun

in·​fan·​cy ˈin-fən-sē 

plural infancies

1

: the legal status of an infant : minority

2

: the affirmative defense of lacking legal capacity (as to make a contract or commit a crime) because of being too young and especially because one's age is below an age set by statute