The word spike has several meanings:

1. A sharp, pointed piece of metal or wood, like the metal spikes railroad workers hammered through ties to hold train tracks in place. Running shoes designed for track and field have small metal spikes on the bottom to grip the ground better. Beach volleyball players wear shoes without spikes because the sand already provides grip.
2. A sudden, sharp increase. When summer temperatures spike, they might jump from 75 degrees to 95 degrees in just a day or two. During a thrilling moment in a basketball game, your heart rate might spike with excitement. Scientists tracking an earthquake watch their instruments for spikes in seismic activity.
3. In volleyball, to forcefully slam the ball downward over the net toward the opponent's court. A powerful spike is hard to defend against because the ball moves so fast. When players jump high and spike the ball at just the right angle, it can win the point immediately.