paidiskē

This is the ordinary word for the woman who answered the door, tended the courtyard fire, and ran a household's errands in the first century. It grew as a smaller, feminine form of the broader word for a child or a servant (παῖς), and by the time of the New Testament it had settled into one job: naming a female slave, usually a younger one, who belonged to a household.

Most of the time the word simply puts her in the room, and the pattern of where she turns up is worth noticing. She is a minor figure, easy to overlook, and the scene keeps turning on her anyway:

• the girl in the high priest's courtyard who is the first to name Peter as a follower of Jesus
• the doorkeeper who asks the question Peter answers with a lie
• Rhoda, who runs from the gate with true news and is told she is out of her mind
• the household servants a drunken steward starts beating while his master is away

The other thing the word can put in the foreground is not her work but her legal condition, and Paul builds a whole argument on that. In Galatians 4 the slave woman stands over against the free woman, and every use of the word there is about standing, inheritance, and whose child a child is. Acts 16 shows the same thing from another angle: what stirs up Philippi is not the girl's deliverance but the money her owners stop earning from her.

Nothing inside the word decides which of the two is in view. It is one plain word for one social fact, and the sentence around it decides whether the point is the errand she is running or the freedom she does not have.