Answer:
Accelerate-increase in amount or extent.
When I press the gas pedal the car accelerates in speed.
Crucial-decisive or critical, especially in the success or failure of something.
It's crucial for me to pass this test or I will fail the class.
Inhospitable-harsh and difficult to live in
I don't like to go camping because I find the camp grounds inhospitable.
Mere-the smallest or slightest
For my date I like to wear a mere amount of makeup.
Pioneer-a person who is among the first to research and develop a new area of knowledge or activity.
I would like to thank the pioneer who thought of the idea of pizza.