Growing Symbol is a highly visual, progressive feature, primarily used in bonus rounds like free spins, where thephysical size of a designated special symbol (usually a wild) progressively increases (e.g., 1x1 → 2x2 → 3x3) each time a specific condition is met.
The core of this feature, unlike a 'Growth Multiplier' where a number increases, is that the'size' of the symbol itself gets bigger. This clearly shows the player that the bonus round's potential is strengthening and makes them anticipate the explosive rewards upon reaching the final stage.