Fluctuate | v. to be unstable; to rise and fall | Stocks can fluctuate on a daily basis, making it difficult to determine when to buy or sell one.

Galvanizing | adj. thrilling, exciting, stimulating | The galvanizing performance left everyone spellbound.

Geriatric | adj. relating to old age | I became interested in geriatric medicine shortly after my grandfather passed away from cancer.

source: https://blog.prepscholar.com/sat-vocabulary-words