Wiktionary
vb. (context idiomatic English) To avoid, or cancel some event that one has previously arranged with someone.
WordNet
v. ask for permission to be released from an engagement [syn: excuse]
Usage examples of "beg off".
Tall Eyebrow had managed to beg off meetings about minutiae, preferring to save himself for constitutional debate and conversations about trade.
When Ista arrived in the flower-decked entry court to discover Pejar holding a horse for her, it was too late to beg off.
He would beg off messing with the other captains tonight, to ensure he had a clear head for the firing in the morning, but for now a short break to recruit his strength before an arduous couple of weeks was just the thing.
It was nine o'clock at night and he had managed to beg off in the middle of his overtime at the lumberyard to rush home.