A handmaid, also known as a handmaiden, was a type of servant.
Katarina served as a handmaid to Cassandra. (TV: The Myth Makers [+]Loading...["The Myth Makers (TV story)"])
The Toymaker referred to Donna Noble and Melanie Bush as handmaidens when they stepped in to support the regenerating Fourteenth Doctor, each holding one of his hands. (TV: The Giggle [+]Loading...["The Giggle (TV story)"])