bouquin

old, worn-out book; any book

Inherited from Middle French boucquain (“old book of little esteem”), from a derivative of Middle Dutch boec (“book”). Either from an unrecorded Middle Dutch *boekijn, a possible variant of the usual interfixed diminutives boecskin, boekelkin; or instead a native French derivation from the Middle Dutch simplex (ultimately from Proto-Germanic *bōks (“book”)) + -in. Compare English book and -kin.

buck (male hare or rabbit)

Inherited from Middle French boucquin (“old he-goat”). By surface analysis, bouc (“he-goat”) + -in.

mouthpiece of a pipe

Inherited from Middle French bouquin (“mouthpiece of a hunting horn”), ultimately from Latin bucca (“mouth”), whence French bouche. Perhaps through the Norman cognate form bouque + -in. Alternatively borrowed from Italian bocchino or Venetan bochin.