The term "post" has several meanings, depending on its context.
1) In a general sense, a post is a long, slender support or structure that is typically used to hold up something else such as a roof, bridge, or fence.
2) Post can also refer to an article or message published online, particularly on social media platforms like Facebook and Twitter.
3) In the context of military service, post refers to a specific duty station or assignment. For example, someone might say they are "on post" while performing guard duties at a particular location.
4) Finally, in some Commonwealth countries, such as Britain and Canada, the term "post" can refer to mail delivery services, particularly those provided by the government, such as Royal Mail in the UK or Canada Post in Canada.