yakisú [jäd͡ʑɪˈzuˑ], transitive verb: “to hurt (s.o. or sthg)”
As I explained yesterday, akimés can mean “to hurt”, but only in its intransitive sense. In Haotyétpi, valency is an important property of a verb, and a verb cannot usually change valency without an explicit voice affix being added to it. This is very different to English, where many verbs can be used transitively and intransitively without a single morphological change.
So akimés can only be used to mean “to hurt” in the sense of “my foot hurts”. If you’d rather say “I hurt my foot”, you need to use another verb, in this case yakisú.
Yakisú is used when it’s the object that is in pain (and that object can be a person or a body part, basically like the subject of akimés), and the subject is the cause of that pain (or its unwitting facilitator, as it often enough happens :-P).
In terms of morphology, yakisú is formed using the verb-forming suffix -su, basically the opposite of -mes (-mes marks attachment, -su marks emission). The y- prefix it also sports is common in verbs that refer to a sensation or a feeling, or verbs referring to the workings of one’s brains (like yortamés: “to remember” and yortasú: “to suppose”). It originates from an applicative voice prefix that isn’t productive anymore.
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