1.NounAn attack (typically nuclear) launched without warning in the absence of a prior attack by one's opponent, with the intention of destroying one's opponent's ability to retaliate.
"During the Cold War, both sides feared that the other was preparing to launch a first strike."
2.NounA first offense by a lawbreaker, as counted by a three-strikes law.
"His first strike was when he stole a car to go for a joyride."
3.NounOne of the first few coins struck from a new set of dies.
"Collectors pay a premium for first strikes in order to get their hands on coins with the crispest possible detailing."