rudderstock

Etymology tree
Proto-Indo-European *h₁reh₁-
Proto-Indo-European *h₁roh₁-(ye-)-tider.
Proto-Germanic *rōaną
Proto-Indo-European *-tḗr
Proto-Indo-European *-trom
Proto-Germanic *-þrą
Proto-Germanic *rōþrą
Proto-West Germanic *rōþr
Old English rōþor
Middle English rother
English rudder
Proto-Indo-European *(s)teyg-
Proto-Germanic *stikanąder.
Proto-Germanic *stukkaz
Proto-West Germanic *stokk
Old English stocc
Middle English stok
English stock
English rudderstock
From rudder + stock.