“Trying to write about love is ultimately like trying to have a dictionary represent life,” says the narrator of David Levithan’s new novel, The Lover’s Dictionary (Farar Straus & Giroux, $18). “No matter how many words there are, there will never be enough.” Be that as it may, Levithan still has a go at it, telling a love story through a series of alphabetical definitions. Thus, under “brash,” his narrator relates a first night together. Under “grimace” he describes the girl’s morning breath. The story is wonderfully scattershot, skipping back and forth in time from sweet beginnings to painful degradation. (Anybody seen Blue Valentine?) And the definitions are sometimes bracingly, horribly honest and sometimes fleet and witty (“antsy, adj., I swore I would never take you to the opera again,” “celibacy, n., n/a.”) Levithan is known for his young adult fiction—most notably, the super twee Nick & Norah’s Infinite Playlist—and The Lover’s Dictionary is his first adult novel. Some of his Dictionary exhibits the super-dramatic, breathless style of teen lit. But its exuberance mostly rings true for us old people, too. At a key turning point in the relationship, the narrator recognizes that, “We have fallen through the surface of want and are deep in the trenches of need.” ERIN K. THOMPSON

Sat., Feb. 5, 7 p.m., 2011