A post bearing a sign that gives information on directions
(cryptic crosswords) A word or phrase within a clue that serves as an indicator, rather than being fodder.
To install signposts on.
The route wasn't signposted, and we got lost on the way.
To direct (somebody) to services, resources, etc.
To indicate logical progress of a discourse using words or phrases such as now, right, to recap, to sum up, as I was saying, etc.
To signal, as if with a signpost