a sudden desire to act without thought about the consequences; a short increase in strength, force

drive, resolve

one of a pair of sharp-toothed wheels on the heels of a rider's boots, used to make the horse go faster

incitement, stimulus

a drink (e.g. coffee, brandy), drug etc that increases bodily or mental activity; anything that encourages a person (e.g. praise, hope of gain)

substance that invigorates