“Half-life” of a drug refers to the time taken for the initial concentration of a medication in blood to reduce by half. Essentially, it is a way of describing how long a drug stays and acts in your body. Drugs with short half-lives last for less time than drugs with long half-lives. Buprenorphine/naloxone (Suboxone) stays in your system for 28-42 hours after sublingual administration (under the tongue), which is the most common route for Suboxone treatment. (Intramuscular, intravenous, and transdermal formulations have varying half-lives in your bloodstream.) This is a lot longer than other opioids, allowing it to prevent withdrawal symptoms in your body for a longer time.
Remember: half-life calculations are but one facet of predicting the duration of stay of a drug in the system, which is more complicated. In general, it takes a week or less for Suboxone to get out of the system entirely.