Final answer:
The root 'gress' refers to stepping, and with the prefix 'pro-', it forms the word 'progress', meaning to step forward. Prefixes change words' meanings and can assimilate in form depending on the letters that follow, as seen in 'aggression'.
Step-by-step explanation:
The root gress means 'step' or 'to step.' When we want to signify movement forward, we use the prefix 'pro-' to form the word progress, which means 'to step forward' or advance in some way. This prefix + root combination is an example of how words are formed in English, helping us understand the meaning by breaking down their parts.
There are several other prefixes and suffixes which, when attached to free stems or bound bases, modify the meaning of the original word to convey different concepts and actions. For instance, the affinity of the prefix ad- often changes to ag- before a stem starting with g, resulting in words like aggression, which includes a doubled g due to this assimilation process. It is important to recognize prefixes such as pro-, ad-, ag-, and others, and understand how they interact with stems and suffixes to create new meanings.