Real Dictionary

yak
countable noun: A yak is a type of cattle that has long hair and long horns. Yaks live mainly in the Himalayan mountains.

yak in American English 1
a stocky, long-haired wild ox (Bos grunniens) of Tibet and central Asia, often domesticated as a beast of burden and for its milk, meat, etc.
noun: a large, stocky, shaggy-haired wild ox, Bos grunniens, of the Tibetan highlands, having long, curved horns: endangered

yak in American English 2
idle or voluble talk
to talk much or idly; chatter
intransitive verb: to talk, esp. uninterruptedly and idly; gab; chatter
noun: incessant idle or gossipy talk

yak in British English 1
noun: a wild and domesticated type of cattle, Bos grunniens, of Tibet, having long horns and long shaggy hair

yak in British English 2
noun: noisy, continuous, and trivial talk or conversation
verb: to chatter or talk in this way; jabber