›in or into a room, building, container, or something similar: What’s inside the big box?I’ll work inside and you work outside.People inside (= working for) the White House get an us versus them mentality.›If you get inside an idea or someone’s mind, you understand the idea or the person: He tried to get inside her mind.inside of›If you do something inside of a particular time, you do it using slightly less than that amout of time: I should be back inside of two hours.