A stock or security that is underperforming. A laggard will have lower-than-average returns compared to the market. A laggard is the opposite of a leader.
Taobiz explains Laggard
In most cases, a laggard refers to a stock. The term can also, however, describe a company or individual that has been underperforming. It is often used to describe good vs. bad, as in "leaders vs. laggards". Investors want to avoid laggards, because they achieve less-than-desired rates of return.