What does the word "slip" in this context mean?

Native speaker’s answer
Rebecca
"Slip" in this context means to forget, although it's usually used as part of the phrase to "slip someone's mind" or "memory". This phrase is said when you forget that something was meant to happen, or when you have forgotten to do something. It implies that you continued through the day without thinking about this thing at all! Ex: It completely slipped my mind that we were going out tonight. I'm not ready yet! Ex: I'm sorry I didn't make it to the meeting. It slipped my mind! Ex: I forgot to pick up the laundry! It totally slipped my mind.