From a poem by Song-dynasty writer Luo Dajing 罗大经 in 《鹤林玉露》: 君恩许归此一醉,傍有梨颊生微涡, describing a smile where a small whirlpool (涡) appears near the pear-shaped cheek (梨颊). A literary or flattering word.
usage
More poetic than the everyday synonym 酒窝 (jiǔwō), which just means dimple for anyone.