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Meaning of main-topmast

main-top•mast

Pronunciation: (mān"top'mast", -mäst"Naut.mān"top'm&schwast), [key]
— n. Naut.
  1. the mast next above the main lower mast.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.