To conceal means to hide something deliberately, keeping it from being seen or known. When you conceal your birthday present from your little sister, you might tuck it in the back of your closet where she won't find it. A magician conceals the coin in her palm before making it “disappear.”

Concealing is purposeful hiding. If you lose your homework in your messy backpack, that's accidental. But if you hide a bad test grade in that same backpack so your parents won't see it, you're concealing it. You are making a choice to keep something from being found. Spies conceal secret messages, architects conceal wiring behind walls, and poker players try to conceal their excitement when they get good cards.

The word often appears in serious contexts. Witnesses might conceal evidence in a crime. Someone might conceal their true feelings to avoid hurting a friend. A company might conceal problems with its products. The opposite of conceal is reveal, meaning to show or make known.

Concealment is the noun form, referring to the act of hiding something or the hidden state itself. Secret compartments provide concealment for valuables. A person's calm expression might be a concealment of their actual nervousness.