agordi

A string, a screw, and a small turn. Agordi is what you do to a violin before you play it: you turn the peg until the string sits at the pitch it should. It takes a direct object, so you agordas the instrument rather than tuning at it, and the result is agordita. The thing you turn is an agordilo, a tuning key, with the -il- tool suffix doing its usual clean job. Agordo is the noun: a tuning, a pitch, a setting.

The figurative sense is not a stretch here - it is the older one. Latin ad cor means to the heart, and accordare meant to bring hearts into agreement long before it meant to bring strings into agreement. Esperanto kept both. So you can agordi a piano, and you can agordi a mood, and neither is a metaphor borrowed from the other. This is the whole of what La Tagiĝo is doing in its first four words:

Agordu la brustojn, ho nia fratar'!

Tune your chests, brothers. Grabowski is asking a crowd to get their voices and their hearts into one key at once, and the verb carries both readings without choosing. It is the opening line of the song, and it is why this word earns a page in a course that has 3,000 slots.

And then the modern job. Agordi is also the ordinary Esperanto verb for configuring a machine: agordi la komputilon, agordi la retumilon, and the settings menu on any Esperanto interface is Agordoj. Nothing new was coined for it - the tuning word simply took the work on, exactly as English tune did in tune the engine. If you use Esperanto software, Agordoj is the word you will meet first, and now you know the violin is underneath it.

Two neighbours. Akordo is a chord, three notes sounding together, and it is the same root with the noun ending straight on it; akordi is to be in agreement. Harmonio is the wider musical and social sense. All three come from the same Latin heart, which is a rare case of a family that stays honest in Esperanto.