This is the 19053rd most frequent Korean word.
아버지도
"아버지도" means "father too" or "also father" in English.
In this sentence, "아버지도" is used to indicate that the father also performed the action (going to school) in addition to others.
아버지도 학교에 가셨다.
Father also went to school.
Here, "아버지도" suggests that father was tired, just like others or as an addition to someone's tiredness.
어제는 아버지도 피곤하셨다.
Yesterday, father was also tired.
In this case, "아버지도" indicates that the father joined the dinner along with other individuals.