That chatty nonno at the bottom of your road who’s determined to stop you for a half-hour lecture about his zinnias each time you pass by? He’s an attaccabottoni.

It means someone who, literally, “attaches your buttons”: the image it conjures up is of someone keeping you a little too close for a little too long, as if they were repairing the jacket you’re wearing. Or, as we’d say in English, buttonholing you.

A literal “button-attacher” for sale on Kijiji. 

In other words, they’ll talk your ear off, whether you want them to or not.

È un tremendo attaccabottoni.
He’s such a windbag.

The nice thing, for those of us who sometimes struggle to remember which ending to use, is that attaccabottoni is invariable: whether you’re talking about a man or a women, one windbag or – heaven forbid – a whole crowd of them, the word doesn’t change.

Camminava rapida per scoraggiare gli attaccabottoni.
She walked quickly to discourage buttonholers. 

In fact there are even self-help guides on how to attaccare bottone with an attractive stranger; but please, please, read the signals and take the hint when you’re pinning anybody – or their buttons – down.