[] to close packaging (= material used to wrap or protect goods) so that the contents cannot get out封闭◆Heat is applied to seal the shrink-wrap.热缩塑料薄膜包装需要加热来封口。to close an envelope by sticking the edges of the opening together封上（信封）◆Make sure you've signed the form before sealing the envelope.确保在封上信封之前你已经在表格上签了名。to make sth definite and final, so that it cannot be changed or argued about使成定局◆They hope to seal the deal with a cash offer of €35 per share.他们希望以每股 35 欧元的现金出价敲定这笔交易。➡ idiom at sign verb●ˌseal sth ˈinto prevent sth that is contained in sth else from escaping把…封在里边◆The food is frozen quickly to seal in the flavour.食品被速冻以便保存其原有风味。self-seal