oscedi

One root, and an odd-looking one. Oscedi has no prefix and no suffix. The os- is not a particle, the -ced- is not the -ced- of koncedi, and there is nothing to decompose. It is a single Latin verb arriving whole, which is worth stating because the shape of the word invites a wrong guess. Say it "os-TSE-di": the c is ts, as it always is in Esperanto.

The Latin behind it is a small free lesson. Oscitare breaks into os, the mouth, and a verb of setting in motion. To yawn is to set the mouth going, which is a fair description. The os in there is the same one that gives English oral, and it is unrelated to the Esperanto buŝo at rank 428, which came from French bouche. Two words for the mouth, from two different Latin roads.

The family and the company it keeps. Oscedo is a yawn as a noun, oscedado the repeated business of yawning through a whole afternoon, oscedema the adjective for someone prone to it. The words around it are the ones you would expect: laca at 884 for tired, dormi at 262, enui at 1,479 for being bored, and nokto at 179. Note that Esperanto, like English, lets a yawn mean boredom as well as tiredness, and politely does not tell you which.