The antonyms for the word "backnumber" are "current," "up-to-date," "contemporary," and "modern." These terms indicate that something is fresh, relevant, and recent rather than old or outdated. For example, a "current" news article will provide the latest information on a particular event, while a "backnumber" article would offer outdated or historical information. Likewise, a "modern" fashion trend is one that is currently popular and new in the market, while the antonym "backnumber" would refer to a style that was popular in the past. Therefore, using antonyms like "current," "up-to-date," "contemporary," and "modern" can help to clarify the timeliness of a topic or idea.