When you look the word "father" up in the dictionary, it is defined as "a male person whose sperm unites with an egg, resulting in conception of a child"*.  Less technical definitions include "a man who adopts or raises a child"*, or "any male acting in a paternal capacity"*.  The word is used interchangeably with dad.  But what constitutes a father or dad?

In answering this question, no single word or term comes to mind.