W: (adj) meaningful [Indirect via meaningless] (having a meaning or purpose) "a meaningful explanation"; "a meaningful discussion"; "a meaningful pause"
S: (adj) mindless (requiring little mental effort) "mindless tasks"
W: (adj) mindful [Opposed to: unmindful] (bearing in mind; attentive to) "ever mindful of her health"; "mindful of his responsibilities"; "mindful of these criticisms, I shall attempt to justify my action"