tusi

The minimal pair of this chapter, and it is one hat wide. Tusi is to cough. Tuŝi, at rank 587, is to touch. On paper the difference is the little circumflex over the s; in the mouth it is the difference between the s of sun and the sh of shoe, so read your Esperanto out loud and the two separate themselves instantly. Read it silently in the x-system, where they are tusi and tusxi, and you will mix them up for a week. This is the same trap ŝelo and ĉelo set two chapters ago, and the same escape route works: sound the word.

Where the confusion actually bites. Tuŝi is far the commoner verb and it turns up inside kortuŝi, to move somebody emotionally, literally to touch the heart. A story that says lia rakonto kortuŝis min is not describing a coughing fit. Watch the hat in your own writing, because both sentences parse.

The family. Tuso is a cough as a thing you have, tusado a bout of coughing that goes on, and ektusi to give one single cough - the sort you produce to make somebody notice you are standing in the doorway.