koncedi

This is the awkward case in the false-seam family, and it deserves the extra sentence. Cedi is a real Esperanto verb, at rank 1,253, meaning to yield or give way. So a learner who splits koncedi into kon- plus cedi has, unusually, found a genuine word on the right-hand side. It is still not a build. Esperanto has no prefix kon- - the prefix meaning together is kun-, with a u, and it never assimilates to kon- the way Latin's com- did. Koncedi is one root, borrowed as a unit, and the fact that Latin assembled it from con- and cedere is history rather than grammar. Same class as inspiri and konsenti: the pieces are real in Latin, invisible in Esperanto.

The near-miss is what makes it teachable. Because cedi exists, the split does not just fail, it fails in a way that changes the meaning. Kun-cedi would have to mean something like to yield together, which is not what conceding is. Conceding is asymmetric: you give ground to somebody who was pressing for it.

Against the neighbours, which are genuinely close.Konsenti is to agree, and it is neutral - you and I simply want the same thing. Agnoski is to acknowledge a fact. Akcepti is to accept what is offered. Koncedi carries the reluctance that none of the others do: you admit the point, or grant the demand, and you would rather not have. That is exactly the English word's flavour too, so the mapping is unusually clean. Koncedo is a concession in both senses - the point given up in an argument, and the commercial concession granted by a state. Nekoncedebla is a useful adjective in a negotiation.