A male partner in an unmarried romantic relationship.
"After dating for a year, Sarah finally told her parents that Mark was officially her boyfriend."
In plain English: A boyfriend is a guy you are dating romantically and usually care about deeply.
"He told his mother that he had found a new boyfriend to go camping with this weekend."
Usage: Use boyfriend to refer specifically to a man, whereas girlfriend refers to a woman; the gender-neutral term significant other works when you do not wish to specify sex or are unsure of it. This word describes a committed but unmarried partnership and should be distinguished from casual dating terms like date or crush which imply less commitment.
The word boyfriend is formed by combining the words boy and friend. It originally referred to a male companion or associate.