What is Geist?
1.
Deutsche for "ghost".
"The haunted house is full of geists."
"Wha?"
"Ghosts I mean."
"Uh, riiiight."
See
2.
n. a religion or an adherent to the belief in a spirit god as opposed to the Deists "clockmaker" god (made the world wound it up and is sitting back watching it unwind), the Theist god, a "human" god who watches and interfers when it feels like it. The Geists god is the spirit or force that organized the world and causes it to run.
I don't belive in God. So you're an atheist! Maybe some force, like magnetism, electricity, or gravity created the world and maybe is present ... Oh! So you're a Geist.
See
3.
To shake one's head side to side in either disappointment or shame.
My wife always geist's me when I fart in bed.
See