trempi

One picture: something goes into a liquid. ReVo puts it in five words - meti ion en akvon aŭ alian fluaĵon, to put something into water or another fluid - and every use of trempi is that picture with different nouns. Transitive, and it takes the thing being dipped, with the liquid arriving under en: trempi panon en vinon, trempi la plumon en inkon, trempi la manon en la riveron.

The accusative after en is doing real work here. Trempi ion en akvon, with the -n, is the dipping motion, into the water from outside it. Trempi ion en akvo, without, would describe something already in there. Esperanto marks direction with the accusative after a preposition of place, and trempi is one of the verbs where the distinction is easiest to feel. The tricky prepositions article sets the rule out in full.

Kitchen register, mainly. This is a food word before it is anything else, and it belongs beside kuirarto seven ranks earlier in the same band. Trempi panon en oleon is what you do at the start of a meal in half of Europe. Trempeti, with the diminutive, is dunking: a quick partial dip, a biscuit in tea. And a trempsaŭco is a dip - the bowl of stuff, not the action.

Two neighbours to keep apart. Trempi is what you do to the thing; sorbi at rank 2,687 is what the thing then does to the liquid, soaking it up. And trempiĝi is the intransitive: the cloth gets soaked, nobody is holding it. One root, three quite different sentences, and the suffixes make all the difference.