Metaphorically, I agree with Peter Duncanson that it probably means
ineffectual, weak, etc.
In fact, the quotation is from some translation of /Les Misérables/.
Here's another translation:
"He had a reasonably good digestion, a brother who was a curé, white hair,
no teeth in his head and no bite in his spirit, a slight tremor that
pervaded his whole body, a Picardy accent, a childlike laugh, a readiness
to take fright, and the general..." (That's as far as Google Books will
let me copy.)
Here's the original:
"Il avait un estomac passable, un frère curé, les cheveux tout blancs,
plus de dents ni dans la bouche ni dans l'esprit, un tremblement de
tout le corps, l'accent picard, un rire enfantin, l'effroi facile, et
l'air d'un vieux mouton."
Literally, "no more teeth in the mouth or in the spirit". Slightly
less literally, "his" instead of "the".
At least we're on topic there at the end.
--
Jerry Friedman