demonstri

Two senses, both of them classroom or laboratory. The dictionary gives demonstri as, first, to describe and explain something by means of specimens or trials, with a teaching purpose; and second, to prove by reasoning. A physics teacher demonstras an experiment. A mathematician demonstras a theorem. A salesman demonstras a car. What all three share is that something is being made evident to somebody.

What it is not is a protest. This matters, because English uses one word for both and gets away with it. In Esperanto the march in the street is a manifestacio, which sits one rank band along at 2,837, and the verb for taking part in one is manifestacii. Demonstri has no protest sense at all. Saying ni demonstris kontraŭ la registaro will be understood by an English speaker and will puzzle everyone else, who will wait to hear what you were showing them.

A false seam, with a real tangle inside it. Demonstri looks like de- plus monstri, and monstro at rank 1,167 is a live word here, which makes the guess almost irresistible. It is wrong: Esperanto's de- is a preposition, not a prefix that builds verbs, and there is no root monstr- meaning to show. The word came over whole from Latin.

And yet the tangle is real in Latin. Monstrare, to show, and monstrum, a portent, both come from monere, to warn: a monster was originally an omen, a sign the gods were pointing at. So montri at rank 175 and monstro at 1,167 and demonstri here are all descendants of the same warning, arriving in Esperanto by three separate doors and staying strangers once inside. Pruvi at 590 is the plain word for prove, and it is what you want nine times in ten.