Question

What does the word “conscientious” mean in the following sentence? Although she was conscientious, or careful, a few errors slipped by.

Answer 1

"Conscientious" here would refer to the woman being careful and thorough about her work. Trying to make sure it was as best as possible, and there would be no screw-ups.

Answer 2

The word conscientious means: "wishing to do what is right, especially to do one's work or duty well and thoroughly. "

The text also follows by saying "or careful, [...]", which might imply that the word was used as a synonym, but most likely indicates that she was actually trying to do everything correctly as much as possible.