kill merely states the fact of death caused by an agency in any manner.
killed in an accident
frost killed the plants
slay is a chiefly literary term implying deliberateness and violence but not necessarily motive.
slew thousands of the Philistines
murder specifically implies stealth and motive and premeditation and therefore full moral responsibility.
convicted of murdering a rival
assassinate applies to deliberate killing openly or secretly often for political motives.
terrorists assassinated the Senator
dispatch stresses quickness and directness in putting to death.
dispatched the sentry with one bullet
execute stresses putting to death as a legal penalty.
executed by lethal gas
Example Sentences
Verb The disease has killed thousands of people. Three people were killed in the accident. a chemical that kills weeds a disease that can kill taking drugs to kill the pain Despite protests, the mayor killed the program. The committee killed the bill. This delay has killed our chances of finishing the project on schedule. She told him to kill the lights. See More
Word History
Etymology
Verb and Noun (1)
Middle English, perhaps from Old English *cyllan; akin to Old English cwellan to kill — more at quell