The word blast has several related meanings:

1. A powerful explosion or the sound it makes. When dynamite detonates during construction, it creates a blast that can be heard for miles. A blast of a car horn is a loud, sudden noise. Scientists might use a controlled blast to break up rock, while a blast from a trumpet announces the start of a ceremony.
2. A strong rush of air or wind. Opening a freezer door releases a blast of cold air. During winter storms, blasts of arctic wind can make temperatures feel even colder. A blast furnace uses powerful air currents to create the intense heat needed for making steel.
3. To break something apart using explosives or great force. Workers might blast through a mountainside to build a tunnel. Water pressure can blast dirt off a sidewalk.
4. An extremely fun time. When someone says they had a blast at your birthday party, they mean they had an absolutely wonderful time. A movie that's a blast to watch keeps you entertained and excited from beginning to end.