It’s not exactly a good word these days, as it has a sinister connotation, much like the word gay, the meaning of which as we know today has nothing to do with what it meant in the past.
Peering at someone could be inferred as looking at someone in a manner that makes them feel uncomfortable.
But, in another sense, to peer is to look at someone or something with difficulty or without concentration.
A peer can be someone of equal age or social standing as you.
Then there’s peer pressure which is the desire by younger people to be the same as others of the same age or social status. And it could lead to underage smoking or drinking to fit it with others.
This is not to be confused with the word pier, which is one of the large or small structures that jut out into the sea, the more notable are at Brighton, and Blackpool.
Sometimes you can tie a boat up.
It can also be a tall structure that holds up part of a floor, or roof.