I'm looking for a polite word for someone who traps you in a conversation. I'd like to avoid suggesting that the person is foolish, just that they continue a conversation in spite of all hints that you need to leave or hang up the phone or get on with what you were doing.
If you want to be polite, go with "garrulous".
If you want to be less formal, go with "motormouth".
Personally, I like "oblivious chatterbox".
I googled the term and found this gem on Twitter:
For an exhausted introvert to be held captive by an oblivious chatterbox - could there be a more acute form of torture?
The action is to
buttonhole (verb) informal oxforddictionaries.com
Attract the attention of and detain (someone) in conversation, typically against their will: “”reporters buttonhole officials coming out of the press secretary’s office””
A description of buttonholing occurred on SE here
It is also known as 'Parson's Farewell' which is the name of a 17th Century dance in which the 'parson' steps up to each of the other dancers, bows and steps back, bows and steps back, bows and steps away; and then moves on to the other partner and says good-bye again, and again.
Buttonhole is what the Ancient Mariner does to the wedding guest,
"The Wedding-Guest sat on a stone:/ He cannot choose but hear; "
www.poetryfoundation.org/poem/173253 And I've often heard the buttonholers described as 'Ancient Mariners.' There's a polite term for you: by the time the talker has worked out whether it's a compliment it will be too late to protest.