A man who has adopted a child, as opposed to a biological father.(noun)
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Use "adoptive father" in a sentence
"And with care, the family savings would stretch to teacher-training college, and the boy would teach others, not carry loads like his adoptive father or scrub floors and iron shirts like his mother."
"“You are Caesar’s equal,” he said slowly, so dazed that he forgot to call his adoptive father Divus Julius."