Definition: Either: 1) Concerned with stones; or 2) Of style, etc; Engraved on stone, esp. monumental stones.
Other: One thing Wallace does which is kind of neat and replicates actual human communication quite well is to have speakers misuse words. It seems that the Director of Composition is here misusing lapidary, or at least employing it in an idiosyncratic fashion. Etymology derives from lapis lazuli, which is a pretty neat looking stone, if you’re into that sort of thing.
SNOOT score: 3
Source: Oxford English Dictionary