Mr Trudeau corrected the student for using the term "mankind" at a Q&A session at the MacEwan University in Edmonton, and recommended "peoplekind" as an alternative.
Mr Trudeau, 46, was answering student questions when a young woman from the World Mission Society Church of God asked whether the Canadian government could ease regulations that limited volunteering with religious organisations.
"We came here today to ask you to also look into the policies that religious charitable organisations have in our legislation so it can also be changed because maternal love is the love that is going to change the future of mankind," she said.
Mr Trudeau politely interrupted the student, saying: "We like to say 'peoplekind', not necessarily mankind."
Mr Trudeau was greeted with applause following his comment.
The woman asking the question took the gesture in good spirit and said: "There we go, exactly."
"We can all learn from each other," Mr Trudeau replied.
Mr Trudeau has been a strong advocate for gender equality as Canadian prime minister, introducing the first gender-equal cabinet during his time in office.
While the mood in the room was complimentary, his comments faced backlash on social media, with some accusing him of being over-zealously politically correct.
