If you say something is happening 'meanwhile' or 'in the meantime' it refers to 'the time in between' something happening and another event. This is a popular phrase and is used often in both social and professional contexts to talk about concurrent events or things happening at the same time as something else or between two other events.

1. Why don't you start cooking dinner now and meanwhile, I'll go down to the shops and pick up something nice for dessert.
2. It had been five years since I last saw Kate, and in the meantime, she had got married and started a family.

1. Delivery of the new computers to the office has been delayed, so they won't arrive until the end of the week now. In the meantime, we'll just have to keep using the old ones.
2. Gary was on the phone in his office trying to salvage the deal, meanwhile, the rest of us waited anxiously for news.