Final Answer:
The word "untouchable" is a compound word, combining the prefix "un-" with the base word "touchable," indicating the opposite of touchable or beyond reach.
Step-by-step explanation:
The word "untouchable" is formed by adding the prefix "un-" to the base word "touchable." The prefix "un-" is commonly used to indicate negation or reversal, changing the meaning of the base word. In this case, "touchable" means capable of being touched, and adding "un-" transforms it into "untouchable," meaning not capable of being touched or beyond reach.