The acronym "PU" can have multiple meanings depending on its context. Here are some possible definitions: 1) PU - Power User, a term used to describe someone who is highly skilled or knowledgeable in using technology, particularly computers and software programs; 2) PU - Post-Ups, a basketball term referring to shots taken near the basket after a rebound or steal; 3) PU - Proof of Use, a requirement for registering a trademark that involves providing evidence of how the mark has been used in commerce.