The term 'serve as a sign of' can be summarized by the word 'BETOKEN', which has 7 letters. BETOKEN is a verb meaning to be a sign or indication of something, usually something that is to come. It is often used to describe a situation in which a certain action or event is seen as a sign of something else, such as a change in the future. For example, a person might say that a certain event betokens a new era in their life.