Refusing to consider something seriously, or ending someone's employment and telling them to leave.
From Latin 'dismittere' (dis- 'away' + mittere 'to send'), literally meaning 'to send away.' It entered Middle English in the 14th century with the meaning of releasing or discharging someone.
The word comes from military language—officers would 'dismiss' troops by sending them away, which is why teachers still 'dismiss' classes, literally commanding them to go away or leave.
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