In the English-speaking world this name is more commonly given to girls. This is due to the American actress Alexis Smith (1921-1993), who began appearing in movies in the early 1940s. It got a boost in popularity in the 1980s from a character on the soap opera Dynasty.
In America, this name received a boost of popularity in 2000 when a character bearing it began appearing on the television series The West Wing.
In Britain the parallel form Alice, derived via Old French, has historically been more common than Adelaide, though this form did gain some currency in the 19th century due to the popularity of the German-born wife of King William IV, for whom the city of Adelaide in Australia was named in 1836.
As an English name, Abigail first became common after the Protestant Reformation, and it was popular among the Puritans. The biblical Abigail refers to herself as a servant, and beginning in the 17th century the name became a slang term for a servant, especially after the release of the play The Scornful Lady (1616), which featured a character named Abigail. The name went out of fashion at that point, but it was revived in the 20th century.
As an English name, Aaron has been in use since the Protestant Reformation. This name was borne by the American politician Aaron Burr (1756-1836), notable for killing Alexander Hamilton in a duel.