Insanable is a word that isn't commonly used in everyday vocabulary. However, it can be understood as something that cannot be made sane or reasonable. The antonyms for this word can be words like manageable, controllable, rational, logical, and sensible. These words imply that things are under control or can be controlled with rational thinking or reasonable actions. When used in the context of mental illness or insanity, antonyms such as sane, stable, and lucid fit perfectly. Additionally, if we talk about a situation or problem, then antonyms such as fixable, solvable, and resolvable can be used to convey the opposite of insanable - something that can be fixed, resolved or solved.