The prefix "a-" is commonly used in the English language and has various synonyms that can be used to convey different meanings. One of the most common synonyms for "a-" is "non-" which is used to indicate negation or absence. For example, "non-profit" means not-for-profit. Another synonym that can be used is "un-" which means not, or the opposite of. For instance, "unhappy" means not happy. Additionally, "dis-" is also a synonym for "a-" and is used to indicate reversal or removal. For instance, "dislike" means the opposite of liking. These synonyms for "a-" add variety and specificity to the English language and make it easier to convey meaning.