Other forms: modularly
Use the adjective modular to describe something that is made up of pieces or parts, like a gerbil's habitat of tubes and cages, or a new house that is delivered in sections and then assembled.
Things like houses, cars, airplanes, and computers are all often constructed in a modular way. Rather than being built all at once, they are built in separate parts that get assembled into a finished product. The word modular has been used this way since the 1930s — earlier, it was a purely mathematical term, from the Latin word modulus, or "small measure."