konsterni

The seam is real, but it is not an Esperanto seam. Konsterni looks like kon- plus sterni, and half of that instinct is sound: Latin consternare genuinely is con- plus sternere, to strew or throw down, so the original picture is a person laid flat by news. But neither half works as Esperanto. There is no prefix kon- in the language at all - Esperanto's "with, together" prefix is kun-, as in kunveni to meet and kunlabori to collaborate - and while sterni does exist in the big dictionaries meaning to spread out, it is rare enough that nobody builds with it. Konsterni came in from the international vocabulary already welded, and it stays welded.

A false friend of the affix system. This is worth a moment because Esperanto trains you to expect decomposition, and that training misfires on learned Latin loans in a predictable way: konsideri, konstati, konfesi, konsenti all begin with a kon- that is a Latin prefix and not an Esperanto one. The test is simple - can you find the second half as a live Esperanto root that people actually compound with? If not, memorise the word whole and enjoy the etymology as a story rather than a rule.

What it feels like. Konsterni is stronger than surprise and colder than fear. Mirigi is to astonish, which can be delightful; ŝoki is to shock, which is about offence as much as alarm; konsterni is the news that empties you out and leaves you not knowing what to do. It is transitive, so the thing that dismays is the subject: la novaĵo konsternis min. For the state itself, use the passive participle - mi estas konsternita, I am dismayed - or the noun konsterno.