To seal up or close with a seal; to fasten or secure with a wax seal or official mark.
From en- + seal, where seal comes from Old French scel and Latin sigillum (seal mark or ring). The verb means to secure something by sealing it officially.
Before envelopes, wax seals were how you secured important documents and proved their authenticity—'ensealing' a letter meant dripping wax and pressing your ring into it. Every royal and noble document carried the physical, personal mark of the sender's power.
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