Often, when you brown meat (and sometimes other foodstuffs) in a hot pan with some fat, a brown crust forms on the surface of the pan. This brown crust has a lot of great flavor that you want to preserve, either in the liquid you will use to braise the meat or in a sauce you will serve with it.
To do so, once the meat has been removed from the pan, you pour in a splash of liquid and then use a wooden spoon to scrape up and dissolve the crusty stuff. This is called "deglazing" and is an important step in many, many recipes.
I included the instruction "deglaze" in one of the very first recipes I posted here, to which a certain colleague commented, "Whoah, dudeman, you can't use words like 'deglaze.' People, like, totally won't know what you're talking about, bro."
As much as it pained me to take advice offered in such terms, I admitted he might have a point, and avoided the word in favor of a description of the process. However, I have since grown tired of typing out the phrase "scrape up and dissolve all the crusty bits with a wooden spoon" and see no reason to keep doing so when there is a perfectly good word meaning just that.
So, if you saw the word "deglaze" in a recipe and followed a link here thinking "What the heck does 'deglaze' mean?" consider yourself enlightened. No go back to whatever recipe brought you here and cook it!