Formal, respectful term used when referring to one's own deceased father, especially in writing or announcements. Not used for someone else's father.
See also: 亡母
Thank you for all you did for my late father while he was alive.
This shop was started by my late father.
He decided to keep the company running, carrying on his late father's wishes.
Every year at this time, I visit the grave to remember my late father.
亡父 and 亡母 look alike apart from the second kanji, but 亡父 means one's deceased father while 亡母 means one's deceased mother.
Compound of 亡 (ぼう, 'deceased') and 父 (ふ, 'father'). The reading ぼうふ follows standard on'yomi patterns.
On behalf of my late father, I would like to take this opportunity to express my thanks.