Dictionary:

basswood

  (băs'wʊd')

1. See linden.
2. The soft, light-colored wood of any species of linden. It is used in making crates and boxes, in carving, and in millwork.

[bass, linden bark (alteration of BAST) + WOOD¹.]

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The noun has 2 meanings:

Meaning #1: soft light-colored wood of any of various linden trees; used in making crates and boxes and in carving and millwork
  Synonym: linden

Meaning #2: any of various deciduous trees of the genus Tilia heart-shaped leaves and drooping cymose clusters of yellowish often fragrant flowers; several yield valuable timber
  Synonyms: linden, linden tree, lime, lime tree