/ ˈtriːzn; NAmE / (also ˌhigh ˈtreason ) noun
[ U ] the crime of doing sth that could cause danger to your country, such as helping its enemies during a war
► treas·on·able / ˈtriːzənəbl; NAmE / adjective :
a treasonable act
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WORD ORIGIN
Middle English : from Anglo-Norman French treisoun , from Latin traditio(n-) handing over, from the verb tradere .