Lentigo is a medical term that refers to a small, usually flat and brownish spot on the skin. Due to its specific definition, there are no direct antonyms for the word Lentigo. However, some words that represent opposing concepts to lentigoism include clear skin, unspotted, blemish-free or flawless skin. Alternatively, you may use phrases like bright, radiant, luminous, or glowing skin, which goes against the dull brownish tone of a lentigo. Remember that antonyms are words that have opposite meanings or express opposing concepts; for instance, black and white or hot and cold are antonyms.