An informal word for 'dad' or 'papa' — a familiar way to refer to one's father.
「パパ、見て！」と子どもが笑いかけた。
"Daddy, look!" the child smiled and said.
パパは今日早く帰ってくるって言ってたよ。
Dad said he'd come home early today.
父の日にパパに手作りのカードを渡した。
I gave Dad a handmade card on Father's Day.
Colloquially can mean 'sugar daddy' — an older man who provides financial support to a younger partner; context-dependent.
彼女は若い頃、有名なパパに支えられていたと言われている。
It's said that when she was young she was supported by a well-known 'sugar daddy'.
その業界では時々『パパ活』という言葉が使われる。
In that industry the term 'papa-katsu' is sometimes used.