open up
phrasal verbopen up 
- to begin shooting
- Anti-aircraft guns opened up.
 
 - (often used in orders) to open a door, container, etc.
- Open up or we'll break the door down!
 - ‘Open up!’ He hammered on the door.
 
 
open up (to somebody) 
(British English also open out (to somebody))
- to talk about what you feel and think; to become less shy and more willing to communicate
- It helps to discuss your problems but I find it hard to open up.
 - He only opened up to her very slowly.
 
 
open something  up | open up 
- to become or make something possible, available or able to be reached
- The new catalogue will open up the market for our products.
 - The railway opened up the east of the country.
 - Exciting possibilities were opening up for her in the new job.
 
 - to begin business for the day
- I open up the store for the day at around 8.30.
 - I'd just opened up when this guy came in.
 
 - to start a new business
- There's a new Thai restaurant opening up in town.
 - We've just opened up a branch in Madrid.
 
 - to develop or start to happen or exist; to develop or start something
- A division has opened up between the two ministers over the issue.
 - Scott opened up a 3-point lead in the first game.
 
 - to appear and become wider; to make something wider when it is narrow or closed
- The wound opened up and started bleeding.
 - The operation will open up the blocked passages around his heart.
 
 
open something  up 
- to make something open that is shut, locked, etc.
- She laid the book flat and opened it up.