Dear Dad can have many antonyms depending on the context. For example, instead of "Dear Dad," someone might write "Dear Mom," "Dear Guardian," or even "Dear Friend." Alternatively, antonyms to the word "dear" could include words such as "disliked," "hated," or "resented." An opposite meaning for the word "dad" could be "stranger," "enemy," or "oppressor." However, when referring to the beloved father figure, antonyms for "dear dad" may not be necessary. Everyone has different relationships with their parents, so the terms used to address them may vary. Regardless of the wording used, it is important to always show love and respect towards parents.