Dictionary Exercise

unveil

1.unveil something

to remove a cover or curtain from a painting, statue, etc. so that it can be seen in public for the first time

ex:The mayor unveiled a plaque to mark the official opening of the hospital.

2.unveil something

to show or introduce a new plan, product, etc. to the public for the first time

ex: They will be unveiling their new models at the Car Show.

incubator

a piece of equipment in a hospital that new babies are placed in when they are weak or born too early, in order to help them survive

ex: Their baby was so small she spent three weeks in an incubator before going home.

I prefer to use Oxford Advanced American Dictionary, because it looks very clear, and has no excessive advertising. It has clear definition, and its sentence very simple and easy to learn. 
So if I want to inquire word mean in the future, I will still use this one.