The following new words have been recognized by the Oxford, Cambridge and Merriam-Webster dictionaries over the course of 2015.
butt-dial (v.): Inadvertently call (someone) on a mobile phone in one’s rear trouser pocket, as a result of pressure being accidentally applied to a button or buttons on the phone;
emoji (n.): Any small image or icon used in electronic communication;
fur baby (n.): A person’s dog, cat, or other furry pet animal;
hangry (adj.): Bad-tempered or irritable as a result of hunger;
jeggings (n.): A legging that is designed to resemble a tight-fitting pair of denim jeans and is made of a stretchable fabric;
Mx (n.): A title, like Mr. or Ms., used by those who wish to avoid specifying their gender;
photobomb (v.): To move into the frame of a photograph as it is being taken as a joke or prank;
pwn (v.): (Especially in video gaming) utterly defeat (an opponent or rival);
rage-quit (v.): Angrily abandon an activity or pursuit that has become frustrating;
rando (n.): A person one does not know, especially one regarded as odd, suspicious, or engaging in socially inappropriate behavior;
twerk (v.): Sexually suggestive dancing characterized by rapid, repeated hip thrusts and shaking of the buttocks, especially while squatting;
WTF (abbrev.) What the f—! Used especially to express or describe outraged surprise, recklessness, confusion or bemusement;
Bonus entry [from yours truly]:
pocket yoga (n.): what guys do when we get to the cash window at a drive through.