To unlatch means to open something by lifting or releasing the latch that holds it closed. A latch is a simple fastening device, like the metal hook on a gate or the catch on a jewelry box. When you unlatch a gate, you lift the hook so the gate can swing open. When you unlatch a window, you flip the small lever that keeps it shut.

Unlatching is different from unlocking: latches are simpler mechanisms that anyone can open without a key. Think of the latch on a chicken coop door or the hook-and-eye fastener on a screen door. Farm animals sometimes learn to unlatch their own gates, which is why farmers have to use more complicated latches to keep clever goats or pigs from escaping.

The word can also be used figuratively. When someone unlatches their mind to a new idea, they're opening themselves up to possibilities they hadn't considered before, like lifting a mental hook that kept their thinking closed.