hardtack

Từ điển WordNet v3.1 - WordNet Dictionary

noun

1. very hard unsalted biscuit or bread;
a former ship's staple (Freq. 3)
• Syn:
pilot biscuit, pilot bread, sea biscuit, ship biscuit
• Hypernyms:
biscuit
2. a mountain mahogany (Freq. 1)
• Hypernyms:
mahogany, mahogany tree