1. An extremely oppressive, unjust, or cruel ruler.
2. An absolute ruler who governs without restrictions, especially one who seized power illegally.
3. An oppressive, harsh, arbitrary person: My boss is a tyrant.
[Middle English, from Old French, alteration (influenced by -ant, present participle ending) of tyran, from Latin tyrannus, from Greek turannos, absolute ruler, despot, possibly from Luwian tarwanis, ruler; see terə-2 in the Appendix of Indo-European roots.]
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