An inspiration is a product of your thought, like a brilliant idea. If you have the next revolutionary inspiration like the printing press, the telephone, or the computer, you may just change the world.
The noun inspiration can also mean a sudden intuition or idea, or something that arouses your desire to take action. You may find that doing some routine provides inspiration (gets your creative juices flowing), like going for a walk, looking at art, or reading a great poem. Inspiration can also mean breathing in or inhaling.