The antonym for the word "corrugate" is "flatten." Corrugate means to form into ridges or grooves. Flattening, on the other hand, means to make something smooth or level by pressing or smoothing it. Corrugates is often used to describe materials such as metal, cardboard, or plastic that have been intentionally shaped with ridges or grooves in order to add strength or texture. Therefore, flattening these materials might be necessary for certain applications, such as creating a flat surface for printing or packaging purposes. Other antonyms for corrugate include "unwrinkle," "soften," or "smooth.