ekskurso

The other false seam of this band, and a harder one than kajero, because here both halves are genuinely Esperanto. Eks- is a live prefix meaning former: eksedzo is an ex-husband, eksprezidanto an ex-president. And kurso is a real word meaning a course of study. Put them together and you get a perfectly well-formed Esperanto word meaning "a course somebody used to be on".

That is not what ekskurso means. The eks- reading is wrong, and no amount of tidiness in the parse makes it right: ekskurso came in from Latin excursus as one lump, prefix already fused, centuries before Zamenhof gave eks- a job. The Latin ex- in it does mean out, but it is out-running, not ex-anything.

So: two words in one band where both halves are real morphemes and both parses are false. The lesson is not to stop looking for joins. It is to check the meaning that falls out of the join, and to accept that a language which borrows from Latin will keep handing you Latin prefixes that look like Esperanto ones.

Ekskursi is the verb, and ekskursanto the person on the trip. Most congresses run one.