Origin: Latin suffix -al
Sectional has 6 different meanings across 2 categories:
a piece of furniture made up of sections that can be arranged individually or together
"They moved the sectional sofa into their living room, rearranging its individual pieces to create an L-shape around the fireplace."
An item of furniture composed of modular sections; usually specifically a sectional sofa.
"The living room featured a large L-shaped sectional that comfortably fit ten people."
In plain English: A sectional is a large sofa made of separate pieces that you can move around to change its shape.
"We bought a new sectional sofa for our living room to make more space for family gatherings."
Usage: Avoid using this term to describe any room division or map segment, as those meanings belong to the adjective form. It refers exclusively to large, multi-piece sofas that can be rearranged into various shapes.
relating to or based upon a section (i.e. as if cut through by an intersecting plane)
"a sectional view"
"sectional drawings"
related or limited to a distinct region or subdivision of a territory or community or group of people
"sectional tensions arose over slavery"
Relating to a section.
"The sectional view of the engine clearly shows the internal components hidden within the casing."
The word sectional comes from combining the root section with the suffix -al. It entered English to describe something related to a specific part or division of a whole.