a feeling of worry, nervousness, or unease, typically about an imminent event or something with an uncertain outcome. be aware of (something happening) through physical sensation. a natural instinctive state of mind deriving from one's circumstances, mood, or relationships with others. (of a material or article) allowing light to pass through so that objects behind can be distinctly seen. actually existing as a thing or occurring in fact; not imagined or supposed. existence.