1 - talking or tending to talk much or freely; talkative; chattering; babbling; garrulous
2 - characterized by excessive talk; wordy
Origin Latin, 1665, loquacity from loquacitas (talkativeness), derivative of loqui (to speak).
Example from the movie Harry Potter and the Goblet of Fire (where I first heard this word):
Hermione: Harry, you told me you'd figured that egg out weeks ago! The task is two days from now!
Harry: Really? I had no idea. I suppose Viktor's already figured it out.
Hermione: Wouldn't know. We don't actually talk about the tournament. Actually, we don't really talk at all. Viktor's more of a physical being.
Harry laughs and Hermione blushes.
Hermione: I just mean he's not particularly loquacious. Mostly, he watches me study. It's a bit annoying, actually.