When you want to describe something as being the "lightest" it means it weighs the least among a group of similar objects. Some synonyms for the word "lightest" include the terms "fluffiest," "featheriest," and "airy." Another option is to use the term "least heavy" or "least dense." You could also opt for words like "softest," "delicate," or "dainty" to describe something that feels light to the touch. In the sense of color, "lightest" could be replaced with the term "palest" or "most pastel." Whatever word you choose, it should capture the idea of something being weightless or effortless.