We don't have synonyms for caponiere yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are caponier, caponize and caponise.
(n) :
Alternative form of caponier. [(military, historical) A work made across or in a ditch, to protect it from the enemy (as fire from it could cover the ditch), or to serve as a covered passageway (e.g. to outworks).]
(n) :
Alternative form of caponier. [(military, historical) A work made across or in a ditch, to protect it from the enemy (as fire from it could cover the ditch), or to serve as a covered passageway (e.g. to outworks).]