We consider an \(n\)-variate monomial function that is restricted both in value by lower and upper bounds and in domain by two homogeneous linear inequalities. Such functions are building blocks of several problems found in practical applications, and that fall under the class of Mixed Integer Nonlinear Optimization. We show that the upper envelope of the function in the given domain, for \(n \ge 2\) is given by a conic inequality. We also present the lower envelope for \(n = 2\). To assess the applicability of branching rules based on homogeneous linear inequalities, we also derive the volume of the convex hull for \(n = 2\).