sekcio

Three words in this corpus divide things up and they are not interchangeable. Parto is the loosest: any part of any whole, physical or not. A sekcio is a part that somebody drew a line around on purpose - a numbered division of a document, a branch of an organisation, a wing of a museum. Fako is narrower again and is about specialism: a fako is a field of study or a department defined by what it knows, and it is also the pigeonhole in a desk, which tells you how the metaphor got there.

The Esperanto movement uses sekcio in a way worth knowing, because it turns up constantly in the association's own prose: a national or local sekcio is a chapter of a larger body, the branch of the organisation in one country or one town. La brita sekcio is the British branch. Nothing about the word is committee jargon in Esperanto; it is simply the ordinary noun doing ordinary work.

The verb seki does not exist, so do not try to build backwards from here. What Esperanto took from secare is this noun and the surgical sekcii, to dissect, and that is all.