In the city - What city is meant is unknown. Some have supposed it was Nain; some Capernaum; some Magdala; and some Jerusalem.
Which was a sinner - Who was depraved or wicked. This woman, it seems, was known to be a sinner - perhaps an abandoned woman or a prostitute. It is certain that she had much to be forgiven, and she had probably passed her life in crime. There is no evidence that this was the woman commonly called Mary Magdalene.
An alabaster-box ... - See the notes at Mark 14:3.