thumb|right|Twitchers watching a mega—Britain's fifth-ever white-tailed lapwing—and probably adding a lifer to their list; see text for explanation of italicised terms
Twitchers' vocabulary is the set of jargon words used by twitchers (committed birdwatchers who travel long distances to see a new species to add a species to their "life list", year list or other list). Some terms may be specific to regional birding communities, and not all are used due to dialectic and cultural differences.
Terms
;Big Day: a birding event in which a birder or team of birders tries to see as many species of birds as possible within a calendar day.
;BVD: "Better View Desired", describing a lifer that was observed well enough to identify, but not enjoy.
;To pull an Easterla (California): to find a ridiculously rare vagrant in a place with no vagrant potential whatsoever. As in: "A first state record of yellow-browed warbler in Alpine County? How did a Sibe end up 160 miles inland alongside a mountain stream?! And how was it even found?!?"
;Trash bird: a bird that is so common to an area it becomes annoying and is largely ignored by birders (as the European starling, rock pigeon, or house sparrow). Sometimes used sarcastically, as in "You're excited about seeing a bald eagle? It's a trash bird for us in Alaska."
;Twitch: the act of traveling a long distance to see a rare bird. Synonymous with chase.
;Vagrant: a stray far from normal ecological range.