kuumaks
Kuumaks is the translative case form of the Estonian adjective kuum, meaning hot. In Estonian grammar, translative forms are used to express a change of state or condition, often with verbs that indicate becoming something. The suffix -ks attaches to the stem to signal this transition into a new state.
Kuumaks is typically used in predicates describing a process of change. For example, Vesi muutub kuumaks, meaning
The translative case is one of several Estonian grammatical cases that express state changes, and kuumaks parallels
In summary, kuumaks is a grammatical form rather than a separate concept, used to denote a change