To nab means to catch or grab someone or something, often quickly or cleverly. Police officers might nab a thief who's been stealing bikes around the neighborhood. You might nab the last chocolate chip cookie before your brother gets to it, or nab a seat on the bus just as someone else was heading for it.

The word has an energetic, slightly playful quality to it. When detectives finally nab a criminal they've been tracking for weeks, there's a sense of triumph in catching someone who's been hard to catch. A baseball player might nab a line drive headed for the outfield, snatching it out of the air with perfect timing.

Nab works especially well when you're talking about catching something that might get away. If you spot a rare Pokémon in a game, you'd want to nab it before it disappears. The word suggests both speed and success: you saw your chance, you moved fast, and you got what you were after.