to wit idiom formal
就是；即
used to make clearer or more particular something that you have already said
She's starting to see the effects of the disease, to wit: her memory is less reliable and she can't always find her way home after going somewhere. 她开始意识到这种疾病对她的影响，就是她的记忆变得不可靠，而且有时候出门之后找不到回家的路。