A female pig that has not yet produced a litter is called a gilt.
In standard pig-production terminology, a gilt is a young female pig before her first farrowing, the term used for giving birth to piglets. After she has produced a litter, she is generally called a sow. These terms describe reproductive status rather than a specific breed or exact age.
A boar is an adult male pig, while a barrow is a castrated male. The word “gilt” can therefore be confused with “sow” when people use both loosely for female pigs. Commercial farms track gilts carefully because their first breeding, pregnancy, and litter establish important information about reproductive performance and herd management. Piglets are commonly called piglets regardless of sex.