1. improve or increase something
When something is given a 'boost', it improves in performance or outcome. You can 'boost sales', or 'boost the quality' of something - and, of course, you can 'Boost a Post' on Facebook. This action is designed to increase the reach of the post and improve its performance in terms of recognition. A person can be given a 'boost of confidence', or you can say that something 'boosted your confidence'. This means that it made you feel better about yourself and improved your outlook for the future.