No, it is not appropriate to describe the condition of weightlessness as the condition of masslessness.
Weightlessness is a condition in which a body does not feel its own weight. The apparent weight of a body is given by, \[W’=W-ma=mg-ma\]
So, if the vertical acceleration of the body is equal to the acceleration due to gravity, then the apparent weight becomes zero and the body feels weightlessness. But even at that condition, the matter is still there (without any addition or deduction). Since mass is the amount of quantity of matter, mass neither decreases nor increases. Thus, weightlessness does not mean masslessness.