Here's what I've got this week from Clouds of Witness by Dorothy L Sayers:
Supererogation: the act of performing more than is required by duty, obligation, or need (p, 193)
Context: After a brief statement that he intended, not merely to prove his noble client's innocence but (as a work of supererogation) to make clear every detail of the tragedy, Sir Impey Biggs proceeded without further delay to call his witnesses.
Corbel: is a piece of stone jutting out of a wall to carry a weight (definition & image from Wikipedia); sometimes with the images of angels or gargoyles or the like.
Context: [Mr. Murbles] leaned back in his seat smirking like a very neat little grotesque from a Gothic corbel. (p. 195)