"No sé cómo definir este objeto."
Translation:I do not know how to define this object.
After studying many similar examples, it appears that "como" is used when the infinitive verb is transitive (has an object)": no sé cómo definir este objeto.
"como" is left out when the infinitive verb is intransitive (does not have an object): no sé nadar (I don't know how to swim).
Maybe, if you're talking about computer programming. https://www.google.com/search?q=%22define+this+object%22