The opposite of "un constraints" is "limitations" which is the scope or extent of an object, event or action. Limitations are what restrict us from taking full advantage of the advantages that come our way. Another antonym for "un constraints" is "barriers" which are obstacles that hinder the progress or movement of an individual or group. Barriers can be physical, mental, social, or emotional. Thirdly, "restrictions" are the antonyms of "un constraints". Restrictions are imposed by individuals or authorities to control behavior, movement, or access to resources, thereby limiting the freedom of individuals. Lastly, "confinements" which implies being held in a small space or being limited to a particular setting or situation is the opposite of "un constraints".