"To moisturize the lips" means to apply a product, like lip balm or moisturizer, to keep the lips hydrated, soft, and prevent them from becoming dry or chapped. Full definition
For hydration and shine, pat Baby Lips Moisturizing Lip Balm in Quenched onto lips. (makeup.com)
Dark Floral Shift by Amanda Uprichard Sam Edelman Stillson Pump Kendra Scott «Lee» Small Drop Earrings Chubby Stick Moisturizing Lip Colour Balm in «Mega Melon» Fall is a tricky season to dress for. (lifeunsweetened.com)
I was at Sephora buying stocking stuffers yesterday and came across the Clinique Chubby Stick Moisturizing Lip Color Balm. (thefashionablehousewife.com)