From a New Yorker review:
"...Any viewer of Catherine Keener’s lambent performance in “Capote” is prepared to believe that she possesses all these traits [composure, dignity, maturity of spirit, morality, sober-mindedness], but they would not naturally recommend her for an authentic portrayal of the plain and sometimes stubborn Harper Lee, the subject of Charles J. Shields’s biography, Mockingbird (Holt; $25)."
Although I myself had never, ever heard or read this word before, I am proud to report that it means "marked by lightness or brilliance, especially of expression."
It comes from the Latin verb lambere , to lick, and has alternate definitions of
1. playing lightly on or above a surface: flickering
2. softly bright or radiant."
Of course we must also note that, if this were a question on the SAT, we would realize that the singular "viewer" in the sentence above does not agree with the plural pronoun "they." Tsk Tsk Tsk.