We don't have synonyms for french drain yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are french braid.
(n) :
A shallow trench, sometimes lined with tile or containing a perforated pipe, backfilled with gravel and then covered over, used to collect and channel runoff water.
(n) :
A gravel-filled corridor with a perforated pipe running through it that runs against the foundation footings of a building, used to collect ground water and drain it away from the building's interior.
(n) :
A shallow trench, sometimes lined with tile or containing a perforated pipe, backfilled with gravel and then covered over, used to collect and channel runoff water.
(n) :
A gravel-filled corridor with a perforated pipe running through it that runs against the foundation footings of a building, used to collect ground water and drain it away from the building's interior.