Stifled is an adjective for anything that's been squashed or smothered. You might have a stifled ambition to be an astronaut that you never admitted to others.
Something stifled is stunted, or prevented from growing. If your mother never let you read books or climb trees, your childhood curiosity might have been stifled. Perhaps your career was stifled because you were constantly daydreaming about being an astronaut, and so failed to do your job well.