Able to cause death; deadly. It can also describe something extremely dangerous or harmful.
From Latin *letalis* or *fatalis* meaning “deadly,” from *letum* (death). It entered English through scholarly and legal language.
‘Lethal’ is often used for weapons and doses, but we casually say ‘lethal combination’ for things like speed and texting. That shows how our language quietly warns us when ordinary actions cross into truly dangerous territory.
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