mainstay
nounA chief support.
nounA strong rope that serves to steady and support the mainmast of a sailing vessel.
nounplural All the stays which give support to the main lower mast, maintopmast, and maintopgallantmast.
nounThe rope which secures the head of the mainmast of a vessel forward.
noun2. Chief support; main dependence: as, their mainstay is fishing.
nounThe stay extending from the foot of the foremast to the maintop.
nounMain support; principal dependence.
nounA
A
a prominent supporter