The term SPRING SUDDENLY can be broken down into three crossword solutions: POUNCE (6 letters), CATAPULT (8 letters), and DART (4 letters). POUNCE is an action taken by cats, where they quickly jump onto something or someone. CATAPULT is a device used to launch objects, often used in warfare. Finally, DART is an object that is thrown with a quick motion, usually for the purpose of hitting a target. All three words describe a sudden, quick movement, which is what the term SPRING SUDDENLY implies.