"Unconstraint" is a word in ENGLISH

A complete giving up to natural impulses; freedom from artificial constraint; careless freedom or ease.

Freedom from constraint, formality, difficulty, embarrassment, etc.; facility; liberty; naturalness; -- said of manner, style, etc.; as, ease of style, …

Freedom from effort, constraint, or formality; -- said of style, manner, etc.

The state of being familiar; intimate and frequent converse, or association; unconstrained intercourse; freedom from ceremony and constraint; intimacy; as, …

Exemption from constraint or oppression; freedom; liberty.

The power of choice; freedom from necessity; freedom from compulsion or constraint in willing.

Beyond the limits of concealment, confinement, privacy, constraint, etc., actual of figurative; hence, not in concealment, constraint, etc., in, or …