A truckload is the amount of something that fills up a truck, which can be an enormous quantity. When a store receives a truckload of new books before the holidays, workers may use forklifts to unload all the boxes. Construction crews order truckloads of gravel, sand, or lumber when building something big.

People also use truckload to emphasize that there's a lot of something, even when no actual truck is involved. If your teacher says you have “a truckload of homework,” she means you have way more than usual. When someone says “thanks a truckload,” they're using exaggeration for effect, similar to saying “thanks a million.”

The opposite is a small amount. While you might order a truckload of mulch for a large garden, you'd probably just buy a few bags for a small flower bed.