means The quality of being intensely clear, bright, or lifelike — whether in color, detail, or the sharp realness of a mental image or description.

from From Latin vividus, "lively, animated, full of life," rooted in vivere, "to live" — the same vital spring that feeds words like survive, revive, and vivacious. English borrowed vivid in the 17th century, first for things bursting with life, then for colors and impressions so strong they seemed alive. Adding -ness simply turns the bright adjective into a thing you can possess: the very liveliness of life itself, bottled.