What is 'hair that doesn't move'?

[OrangeFootedScrubfowl]

Mentioned many times on the mumsy thread.
I hope the thread about a thread thing is Ok. It's a genuine question!

Hairsprayed to immobility (often short, permed hair).

Maggie Thatcher type hair, sprayed within an inch of its life to stay in place!

Oh sprayed! Ok!

I saw a woman at the school the other day. She had a booufy bob that was like a mahogany helmet. Dreadful. She'd really ott and dated make up as well. Made her look ancient when I know for a fact she's only a bit older than me.