to open something, especially a door that is locked (= fastened with a lock) using a key or an electronic device

I think I left the garage door unlocked. 我觉得我忘了锁上车库门。

to enter a password or number in order to be able to use a mobile phone

You need to know the secret PIN to unlock your mobile phone upon power up. 您需要知道密码才能在开机时解锁您的手机。

to make a mobile phone able to be used on any mobile phone network

Once your phone is unlocked, you can buy and change SIM cards as you travel. 手机解锁后，您可以在旅行时购买和更换SIM卡。

to make the imagination more active, producing interesting ideas and images

One of poetry's functions is to unlock the imagination. 诗歌的功能之一便是开启想象力。