something that is not interesting to you or that annoys you:
Waiting is a bore.
You'll find it's a terrible bore.
someone who is boring, especially because they talk too much about themselves or about things that do not interest you:
He turned out to be a crashing bore (=used to emphasize that someone is very boring).
the measurement of the width of the inside of a long hollow object such as a pipe or the barrel of a gun:
Take a length of piping with a bore of about 15mm.
a fine bore tube
a wave of water that moves quickly along a river from the sea at particular times of the year:
the Severn bore