prilabori

Pri- is one of the quietest and most useful pieces of Esperanto grammar, and prilabori is the clearest place to watch it work. The rule is short: take a verb that needs the preposition pri to reach its topic, bolt pri- on the front, and the topic becomes a plain direct object.

Watch the accusative appear in the right-hand column. That is not decoration - it is the whole point. The oblique object has become a direct one, so it takes -n, and the verb has gone from intransitive to transitive in one move - which is the same machinery, arriving by a different door, as transitivity.

The meaning that results is "to work on something until it has changed": to process a raw material, to till a field, to work up a draft. A factory prilaboras its inputs, a farmer prilaboras the soil, an editor prilaboras a manuscript. Where English needs process, till, work up, treat and dress - five verbs for one idea in five settings - Esperanto uses the one word and lets the object say which setting you are in.

Prilaboro is the processing, prilaborita means processed, and prilaborado is the ongoing activity. The prefix itself takes the same shape everywhere, so once you have seen it here you have seen it on every verb that will ever want it.