Shining brightly with little flashes of light; glittering and shimmering.
From 'sparkle' (from Old Norse 'spraka' meaning to crackle) + '-y' suffix. A casual, informal adjective that became more common in modern English.
Glitter's addictive sparkly appeal actually triggers the same visual processing system that makes us notice moving things—evolutionary leftover from ancestors who had to spot movement (predators or prey) in peripheral vision.
Complete word intelligence in one call. Free tier — 50 lookups/day.