Conversation so far:
What was Girl power?
The phrase girl power was a label for the particular facet of post classical neo-feminist empowerment embraced by the band.
How was the Spice Girls related to girl power?
The phrase was regularly uttered by all five members of the Spice Girls—although most closely associated with Halliwell—and was often delivered with a peace sign.

Question: Did they coin the term girl power?
Self-contained rewrite: Did Spice Girls coin the term girl power?