When you can touch something, it's tangible: "I need tangible proof that aliens exist — I want to shake their little green hands!"
Tangible is from Latin tangere "to touch," and it simply means something that can be touched or felt, though it can be used in metaphorical senses: "tangible assets" have a value that can be precisely measured, and "tangible grief" can be clearly sensed by an onlooker. So you might not need to physically touch something for it to be tangible, but it has to be grounded in the real world of facts: "Has the teen pop star demonstrated any tangible ability to sing?"
adj perceptible by the senses especially the sense of touch
capable of being perceived by the senses; not abstract or imaginary
producing a sensation of touch
adj capable of being perceived; especially capable of being handled or touched or felt
easily perceived by the senses or grasped by the mind
capable of being perceived by the mind or senses