There are numerous synonyms for the phrase "increasing in size." One of them is "expanding," which is often used to describe things that become larger in volume or surface area. Another synonym for "increasing in size" is "enlarging," which is often used to describe things that become larger in physical size or mass. Some other synonyms include "augmenting," "magnifying," "dilating," "swelling," "growing," "multiplying," and "amplifying." All of these words convey the idea of something increasing in size, and can be used interchangeably to describe a wide variety of objects or phenomena.