Some of the new definitions, per the Oxford University Press blog:
cyberbullying: n. the use of electronic communication to bully a person, typically by sending messages of an intimidating or threatening nature.
jeggings: pl. n. tight-fitting stretch trousers for women, styled to resemble a pair of denim jeans.
mankini: n. (pl. mankinis) a brief one-piece bathing garment for men, with a T-back.
retweet: v. (on the social networking service Twitter) repost or forward (a message posted by another user). n. a reposted or forwarded message on Twitter.
woot: exclaim. informal (especially in electronic communication) used to express elation, enthusiasm, or triumph.