Meanwhile means during the same time that something else is happening, often in a different place or involving different people. If your dad is cooking dinner in the kitchen, meanwhile your mom is helping your sister with homework upstairs, both things are happening at once.

The word helps connect two simultaneous events in a story or explanation. A book might say: “The astronauts prepared for liftoff. Meanwhile, back on Earth, mission control monitored every system.” It's like splitting the screen in a movie to show what's happening in two locations.

You can also use meanwhile to shift attention between parallel situations: “I finished my math homework. Meanwhile, my brother was still struggling with his first problem.”

In the meantime means almost the same thing but often suggests filling time while waiting: “Dinner won't be ready for an hour. In the meantime, you can play outside.” Both phrases help readers or listeners keep track of multiple things happening during the same period.