(a.) That may be known; capable of being discovered, understood, or ascertained.

apparent appraisable apprehensible ascertainable assessable calculable clear cognizable comprehensible computable conceivable concrete detectable determinable discernible discoverable distinguishable estimable evident fathomable gaugeable graspable knowable manifest material measurable mensurable meterable noticeable numerable observable obvious palpable perceptible plain ponderable prehensible quantifiable quantizable real recognizable seizable sensible solid substantial substantive tangible understandable weighable