The word "bore" in English has several diverse meanings, not all of them in everyday use, but the most common use is as in Webster 1913's write-up (noun, sense six), is someone who is boring, who causes weariness and ennui, who is tiresome.

Boring versus bore

A bore is a man who deprives you of solitude without providing you with company.
Gian Vincenzo Gravina (1664 - 1718)

To be a bore, it is not enough to be uninteresting. A bore demands attention and then squanders it. They may be interesting, but are are less interesting than they think they are.

Bores and other verbal creatures

"A gossip is one who talks to you about others; a bore is one who talks to you about himself; and a brilliant conversationalist is one who talks to you about yourself"
Lisa Kirk (American Actor, 1925-1990)

An orator is a public speaker, person who is able to get up and address a crowd of people. They will be the only one speaking for most of the time.

A raconteur is someone who "excels in telling stories and anecdotes". They are able to tell entertaining stories. These may be anecdotes that they regularly tell. Other conversation will occur, but at times the raconteur will be focus of attention. A good raconteur will gauge the interest of the listeners, and adapt the delivery and content to the audience.

A conversationalist is able to hold a conversation, which is a two-way process. They deliver wit and wisdom, but will also make the other person feel interesting. They draw out what the other person has to talk about, and will listen at least as much as they speak.

A bore just talks at you, flattening the conversation underfoot. It's a kind of egotism, of inconsiderateness. It's a social lack, an insecurity; not being able to yield the floor, needing to monopolise the conversation.

How to avoid being a bore

Bore, n.: A person who talks when you wish him to listen.
Ambrose Bierce, The Devil's Dictionary

Unless you have been invited to speak at a podium, you shouldn't be the only one who talks. Try to be a conversationalist or a raconteur. Relate to people, don't broadcast. Look for signs of boredom in your audience. Trying harder won't help; the problem could be that you are trying too hard already, causing not solving the problem.

If you've been talking more then everyone else, take a breath and see if anyone else has a go. Give up a bit of control. Ask a question, especially ask someone about themselves. Try to both give and take information. Try to bring out other people's conversations; don't pry, but see if other people have things that they want to say. Be interested as well as interesting.

How to avoid a bore

Don't try to compete by giving an equally self-centred speech, this just encourages them to further competition and makes you a bore too. Nobody will appreciate the ensuing pissing contest. Instead, look around for someone else who also looks bored. Talk to them. Failing that, find an appropriate point to leave. Don't wait for the bore to finish talking, it's not going to happen soon enough.