laboratorio

The relationship is real; the seam is not. Labori is to work, at rank 188. Laboratorio is a laboratory. They are cousins, and not by accident: Medieval Latin laboratorium is literally "a place for working", built on the same laborare that gave Esperanto its verb. So the resemblance you noticed is telling you the truth about the history. What it is not telling you is how to build the word, because -atorio is not an Esperanto suffix and never has been. Break laboratorio at the seam and you get labor- plus something that does not exist.

Compare what Esperanto would have produced. The suffix for a place where an activity happens is -ej-, so a workplace is laborejo, and that is a perfectly current word: a factory floor, an office, wherever your job happens. A laboratory is not a laborejo; it is a laboratorio, borrowed whole from the international vocabulary because every language in the source pool already had it. This is the language making a trade it makes often: the built word is available and free, but the international word is recognisable to a chemist in six countries, and for technical vocabulary that wins. Laborejo and laboratorio sit side by side without competing, because they mean different things.

This is the inspiri class. A borrowed root whose Latin ancestor decomposes cleanly, and whose Esperanto surface does not. You will meet it constantly in the scientific and administrative vocabulary: observatorio (from observare, and observi is the Esperanto verb), direktoro, redaktoro, konservatorio. In each case the Latin analysis is worth knowing because it makes the word memorable, and the Esperanto analysis is worth refusing because it produces roots that are not there.

Working in one. Laboratoria is the adjective, so laboratoria testo is a lab test and laboratoriaj kondiĉoj are laboratory conditions. Laboratoriisto is a laboratory technician, using -ist- on the borrowed root without any trouble at all, which shows the root is fully naturalised even if it was not built here. The word abbreviates to laboratorio in full every time, incidentally: Esperanto has no equivalent of the English clipping "lab", and labo would be read as nothing.