We all experience this in our lives. Remember the new football team you heard about on the TV? Or the day your smart friend explained you what a placebo is? And then all of a sudden, you see and hear this word everywhere- placebo -placebo!
Why is the universe flashing this word before you all of a sudden? Weird isn't it? Well does that mean the word did not exist before it came to your notice? No. Its just your mind playing games with you.
Whenever you learn a new word or term, your brain tries to focus on its occurrence in the future, which you otherwise would have ignored. And this is an actual phenomenon called as- The Baader-Meinhof.